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 A274511 #10 Jul 06 2016 00:55:57
%S A274511 1,3,7,4,7,2,10,9,6,15,11,14,3,5,11,12,8,17,19,5,7,21,21,4,34,25,5,9,
%T A274511 6,20,32,17,31,40
%N A274511 a(n) is the only number m such that 7^(2^m) + 1 is divisible by A273948(n).
%t A274511 t = Select[Prime@ Range[3, 10^7], IntegerQ@ Log2@ MultiplicativeOrder[7, #] &]; Table[SelectFirst[Range@ 100, Divisible[7^(2^#) + 1, t[[n]]] &], {n, Length@ t}] (* _Michael De Vlieger_, Jun 29 2016, after _Arkadiusz Wesolowski_ at A273948 *)
%o A274511 (PARI) forstep(p=3, 10^15, 2, if(!Mod(p, 7)==0, if(isprime(p), o=znorder(Mod(7, p)); x=ispower(2*o); if(2^(x-1)==o, print1(x-2, ", ")))));
%Y A274511 Cf. A273948.
%K A274511 nonn,more
%O A274511 1,2
%A A274511 _Arkadiusz Wesolowski_, Jun 25 2016