This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A145044 #18 Sep 04 2023 15:27:20 %S A145044 13,61,2281,3217,23209,44497,132049,13466917,30402457,42643801 %N A145044 Primes p (A000043) such that 2^p-1 is prime (A000668) and congruent to 271 mod 6!. %C A145044 Mersenne numbers (with the exception of the first two) are congruent to 31, 127, 271, 607 mod 6!. This sequence is a subsequence of A000043. %t A145044 Select[MersennePrimeExponent[Range[47]], PowerMod[2, #, 6!] == 272 &] (* _Amiram Eldar_, Mar 22 2020 *) %Y A145044 Cf. A000043, A000668, A124477, A139484, A145038, A112633, A145041, A145042, A145044, A145045, A145046. %K A145044 nonn,more %O A145044 1,1 %A A145044 _Artur Jasinski_, Sep 30 2008 %E A145044 a(10) from _Amiram Eldar_, Mar 22 2020