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 A178995 #30 Jun 05 2025 16:04:34
%S A178995 3,5,7,9,11,20,28,62,161,204,471,505,881,1810,1812,2506,3321,6809,
%T A178995 9272,15131,17449,25250,27989,36082,53309,64970,66354,69646,96080,
%U A178995 176059,451810,549633
%N A178995 Numbers k such that 3^k (mod 2^k) is prime.
%F A178995 A002380(a(n)) = A178985(n). - _Amiram Eldar_, Jul 18 2021
%t A178995 fQ[n_] := PrimeQ@ PowerMod[3, n, 2^n]; k = 1; lst = {}; While[k < 15001, If[fQ@ k, AppendTo[lst, k]]; k++]; lst
%o A178995 (PARI) for(n=1, 10^5, if(ispseudoprime((3^n)%(2^n)), print1(n, ", "))) \\ _Felix Fröhlich_, Jun 05 2014
%Y A178995 Cf. A002380, A178985.
%K A178995 nonn,more
%O A178995 1,1
%A A178995 _Robert G. Wilson v_, Jan 03 2011
%E A178995 a(20)-a(23) from _Felix Fröhlich_, Jun 06 2014
%E A178995 a(24)-a(28) from _Amiram Eldar_, Jul 18 2021
%E A178995 a(29) from _Michael S. Branicky_, Jun 08 2024
%E A178995 a(30)-a(32) from _Henri Lifchitz_, Jun 05 2025