This will allow you generate a filter list based on live registry data.
(You can also use a regular 'whois' client against filtergen.dan.me.uk to get the same output)

Options:	Enable Debug Mode Generate IPv6 Filter Generate cisco ios-xr juniper force10 mikrotik prefix-list called       Permit up-to prefix size: / (CIDR size, e.g. 24 or 64)
Data Source:	RIPE RADB APNIC
AS-SET to Query:

Output from Filter List Generator:

%
% Filter List Generator
% Copyright(c) 2021, Daniel Austin MBCS
%
% usage:
%   [-D] [-6] [-RIPE | -RADB | -APNIC] [-f filtername -t filtertype [-upto N]] as-set
%
% -D for DEBUG mode (shows working calculations)
% -6 for IPv6 filter generation
% -RIPE for whois.ripe.net lookups
% -RADB for whois.radb.net lookups
% -APNIC for whois.apnic.net lookups
% -f will generate a cisco-style filterlist called 'filtername' (use -t filtertype as follows)
%      cisco (default)
%      iox-xr
%      juniper (basic support)
%      force10
%      mikrotik
% Additionally, if using -f/-t you may specify -upto N where N is the prefix size to permit up-to
%
% Using whois.radb.net for lookups
% Generating filter list for 'AS8075'
102.133.0.0/16
102.133.0.0/17
102.133.128.0/17
102.37.0.0/16
102.37.0.0/17
102.37.128.0/17
104.146.128.0/17
104.208.0.0/13
104.40.0.0/13
104.47.19.0/24
108.140.0.0/14
111.221.100.0/22
111.221.100.0/23
111.221.100.0/24
111.221.101.0/24
111.221.102.0/23
111.221.102.0/24
111.221.103.0/24
111.221.104.0/21
111.221.104.0/22
111.221.104.0/23
111.221.104.0/24
111.221.105.0/24
111.221.106.0/23
111.221.106.0/24
111.221.107.0/24
111.221.108.0/22
111.221.108.0/23
111.221.108.0/24
111.221.109.0/24
111.221.110.0/23
111.221.110.0/24
111.221.111.0/24
111.221.112.0/20
111.221.112.0/21
111.221.112.0/22
111.221.112.0/23
111.221.112.0/24
111.221.113.0/24
111.221.114.0/23
111.221.114.0/24
111.221.115.0/24
111.221.116.0/22
111.221.116.0/23
111.221.116.0/24
111.221.117.0/24
111.221.118.0/23
111.221.118.0/24
111.221.119.0/24
111.221.120.0/21
111.221.120.0/22
111.221.120.0/23
111.221.120.0/24
111.221.121.0/24
111.221.122.0/23
111.221.122.0/24
111.221.123.0/24
111.221.124.0/22
111.221.124.0/23
111.221.124.0/24
111.221.125.0/24
111.221.126.0/23
111.221.126.0/24
111.221.127.0/24
111.221.16.0/21
111.221.24.0/22
111.221.29.0/24
111.221.30.0/23
111.221.64.0/18
111.221.64.0/19
111.221.64.0/20
111.221.64.0/21
111.221.64.0/22
111.221.64.0/23
111.221.64.0/24
111.221.65.0/24
111.221.66.0/23
111.221.66.0/24
111.221.67.0/24
111.221.68.0/22
111.221.68.0/23
111.221.68.0/24
111.221.69.0/24
111.221.70.0/23
111.221.70.0/24
111.221.71.0/24
111.221.72.0/21
111.221.72.0/22
111.221.72.0/23
111.221.72.0/24
111.221.73.0/24
111.221.74.0/23
111.221.74.0/24
111.221.75.0/24
111.221.76.0/22
111.221.76.0/23
111.221.76.0/24
111.221.77.0/24
111.221.78.0/23
111.221.78.0/24
111.221.79.0/24
111.221.80.0/20
111.221.80.0/21
111.221.80.0/22
111.221.80.0/23
111.221.80.0/24
111.221.81.0/24
111.221.82.0/23
111.221.82.0/24
111.221.83.0/24
111.221.84.0/22
111.221.84.0/23
111.221.84.0/24
111.221.85.0/24
111.221.86.0/23
111.221.86.0/24
111.221.87.0/24
111.221.88.0/21
111.221.88.0/22
111.221.88.0/23
111.221.88.0/24
111.221.89.0/24
111.221.90.0/23
111.221.90.0/24
111.221.91.0/24
111.221.92.0/22
111.221.92.0/23
111.221.92.0/24
111.221.93.0/24
111.221.94.0/23
111.221.94.0/24
111.221.95.0/24
111.221.96.0/19
111.221.96.0/20
111.221.96.0/21
111.221.96.0/22
111.221.96.0/23
111.221.96.0/24
111.221.97.0/24
111.221.98.0/23
111.221.98.0/24
111.221.99.0/24
113.197.67.0/24
128.94.0.0/16
13.104.0.0/14
13.107.14.0/24
13.64.0.0/11
131.253.1.0/24
131.253.12.0/22
131.253.128.0/17
131.253.24.0/21
131.253.32.0/20
131.253.5.0/24
131.253.6.0/24
131.253.61.0/24
131.253.62.0/23
131.253.8.0/24
132.245.0.0/16
134.170.0.0/16
135.149.0.0/16
137.116.0.0/16
137.117.0.0/16
137.135.0.0/16
138.239.0.0/16
138.91.0.0/16
143.64.0.0/16
147.145.0.0/16
147.243.0.0/16
148.7.0.0/16
150.171.0.0/16
150.171.0.0/24
150.171.254.0/24
155.62.0.0/16
157.55.0.0/16
157.56.0.0/16
158.158.0.0/16
167.105.0.0/16
167.220.240.0/22
167.220.240.0/23
167.220.240.0/24
167.220.241.0/24
167.220.242.0/23
167.220.242.0/24
167.220.243.0/24
168.61.0.0/16
168.62.0.0/15
169.138.0.0/16
170.165.0.0/16
185.209.209.0/24
185.236.124.0/24
191.232.0.0/13
192.100.104.0/21
192.100.112.0/21
192.100.120.0/21
192.100.128.0/22
192.197.157.0/24
192.48.225.0/24
192.84.159.0/24
192.84.160.0/24
192.84.161.0/24
193.149.64.0/19
193.221.113.0/24
194.41.16.0/20
198.180.95.0/24
198.180.97.0/24
198.200.130.0/24
198.206.164.0/24
198.49.8.0/24
199.103.122.0/24
199.103.90.0/23
199.103.90.0/24
199.242.32.0/20
199.242.48.0/21
199.30.16.0/20
199.60.28.0/24
199.74.210.0/24
20.0.0.0/11
20.135.0.0/16
20.136.0.0/16
20.143.0.0/16
20.150.0.0/15
20.152.0.0/16
20.153.0.0/16
20.157.0.0/16
20.158.0.0/15
20.160.0.0/12
20.184.0.0/13
20.192.0.0/10
20.196.0.0/18
20.203.0.0/17
20.33.0.0/16
20.36.0.0/14
20.37.64.0/19
20.40.0.0/13
20.45.128.0/20
20.45.64.0/19
20.45.64.0/20
20.45.80.0/24
20.46.144.0/20
20.46.192.0/19
20.46.32.0/19
20.46.32.0/24
20.48.0.0/12
20.64.0.0/10
20.74.128.0/17
202.89.224.0/21
202.89.224.0/22
202.89.224.0/23
202.89.224.0/24
202.89.225.0/24
202.89.226.0/23
202.89.226.0/24
202.89.227.0/24
202.89.228.0/22
202.89.228.0/23
202.89.228.0/24
202.89.229.0/24
202.89.230.0/23
202.89.230.0/24
202.89.231.0/24
204.140.80.0/24
204.152.140.0/23
204.231.194.0/24
204.79.135.0/24
204.79.179.0/24
204.79.181.0/24
204.79.195.0/24
204.79.252.0/24
204.95.96.0/20
206.138.168.0/21
206.191.224.0/19
207.46.0.0/19
207.46.128.0/17
207.46.36.0/22
207.46.40.0/21
207.46.48.0/20
207.46.64.0/18
207.68.128.0/18
208.68.136.0/21
208.76.45.0/24
208.76.46.0/24
208.84.0.0/24
208.84.1.0/24
208.84.2.0/24
208.84.3.0/24
208.84.4.0/24
209.185.240.0/23
209.185.240.0/24
209.240.192.0/19
213.199.128.0/18
216.220.208.0/20
216.32.180.0/22
23.100.0.0/15
23.102.0.0/16
23.103.128.0/17
23.103.160.0/20
23.103.64.0/18
23.96.0.0/14
4.128.0.0/12
4.144.0.0/12
4.160.0.0/12
4.176.0.0/12
4.192.0.0/12
4.208.0.0/12
4.224.0.0/12
4.240.0.0/12
40.104.0.0/14
40.104.0.0/15
40.107.142.0/23
40.107.18.0/23
40.108.128.0/17
40.110.0.0/15
40.112.0.0/13
40.119.160.0/19
40.120.0.0/14
40.120.0.0/20
40.123.192.0/19
40.123.224.0/20
40.124.0.0/16
40.125.0.0/17
40.126.0.0/18
40.126.128.0/17
40.126.192.0/23
40.127.0.0/16
40.127.0.0/19
40.64.0.0/15
40.66.0.0/17
40.66.166.0/24
40.67.0.0/16
40.68.0.0/14
40.72.255.0/24
40.74.0.0/15
40.76.0.0/14
40.80.0.0/12
40.95.238.0/23
40.95.86.0/23
40.96.0.0/13
51.10.0.0/15
51.103.0.0/16
51.104.0.0/15
51.107.0.0/16
51.116.0.0/16
51.12.0.0/15
51.120.0.0/16
51.124.0.0/16
51.132.0.0/16
51.136.0.0/15
51.138.0.0/16
51.140.0.0/14
51.144.0.0/15
51.51.0.0/16
51.53.0.0/16
52.105.196.0/23
52.112.0.0/14
52.120.0.0/14
52.125.0.0/16
52.136.0.0/13
52.146.0.0/15
52.148.0.0/14
52.152.0.0/13
52.160.0.0/11
52.224.0.0/11
52.239.232.0/24
52.96.0.0/12
52.96.0.0/14
52.96.38.0/24
52.98.16.0/22
64.4.0.0/18
65.52.0.0/14
66.119.144.0/20
68.154.0.0/15
68.18.0.0/15
68.210.0.0/15
68.218.0.0/15
68.220.0.0/15
70.152.0.0/15
70.156.0.0/15
70.37.0.0/17
70.37.128.0/18
72.144.0.0/14
72.152.0.0/14
74.160.0.0/14
74.176.0.0/14
74.224.0.0/14
74.234.0.0/15
74.240.0.0/14
74.248.0.0/15
91.225.248.0/24
91.225.249.0/24
94.245.64.0/18
98.64.0.0/14
98.70.0.0/15
% end of filter list for 'AS8075' (392 prefixes found) 
% took 0.32 secs for query (0.12 secs of connection time)
% used 1 connections -- 1304 lines of whois data parsed