/usr/share/sagemath/ellcurves/rank15 is in sagemath-database-elliptic-curves 0.8-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 | 164007785374008600847294301252891222936905925387461785510 a 1 [1,0,0,-209811944511283096494753999485,26653992551590286206010035905960909459942897] 15 1
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