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 A274513 #9 Jun 29 2016 03:00:04 %S A274513 0,3,1,5,5,2,7,4,15,14,3,8,19,11,10,24,27,8,19,23,7,16,31,35,4,29,28, %T A274513 11,11,28,35 %N A274513 a(n) is the only number m such that 11^(2^m) + 1 is divisible by A273949(n). %o A274513 (PARI) forstep(p=3, 10^15, 2, if(!Mod(p, 11)==0, if(isprime(p), o=znorder(Mod(11, p)); x=ispower(2*o); if(2^(x-1)==o, print1(x-2, ", "))))); %Y A274513 Cf. A273949. %K A274513 nonn,more %O A274513 1,2 %A A274513 _Arkadiusz Wesolowski_, Jun 25 2016