/usr/lib/mysql-testsuite/std_data/numbers.txt is in percona-server-test-5.6 5.6.22-rel71.0-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9
2 3 5 7 11 13 17 23 29