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 A145038 #9 Sep 04 2023 18:23:06 %S A145038 1,3,7,31,127,271,607,2047,3151,8191,10111,40447,42367,48511,50431, %T A145038 80767,88831,90751,121087,131071,161407,163327,169471,171391,201727, %U A145038 209791,211711,243967,250111,282367,290431,292351,322687,324607,332671 %N A145038 Numbers to which Mersenne primes 2^p-1 can be congruent mod k! (for k > 1). %C A145038 All Mersenne primes are congruent to 1 mod 2!, 1 mod 3! (with the exception of the first one), 7 mod 4! (with the exception of the first one), 7 mod 5! (see A112633), or 31 mod 5! (see A145040). %Y A145038 Cf. A000668, A124477, A139484, A112633, A145040, A145041, A145042. %K A145038 nonn %O A145038 1,2 %A A145038 _Artur Jasinski_, Sep 30 2008