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 A274508 #10 Jul 06 2016 00:55:26 %S A274508 1,3,2,3,7,8,10,15,7,15,11,8,19,4,9,21,10,11,10,26,28,9,29,32,31,38,9, %T A274508 39,34,21,7,31,26,36,5 %N A274508 a(n) is the only number m such that 3^(2^m) + 1 is divisible by A273945(n). %o A274508 (PARI) forstep(p=3, 10^15, 2, if(!Mod(p, 3)==0, if(isprime(p), o=znorder(Mod(3, p)); x=ispower(2*o); if(2^(x-1)==o, print1(x-2, ", "))))); %Y A274508 Cf. A273945. %K A274508 nonn,more %O A274508 1,2 %A A274508 _Arkadiusz Wesolowski_, Jun 25 2016