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 A274003 #9 Jun 07 2016 17:04:21
%S A274003 2,3,15,20,51,68,255,340,771,1028,3855,5140,13107,17476,65535,87380,
%T A274003 196611,262148,983055
%N A274003 Primitive terms (not equal twice a smaller term) of A178751: moduli n such that x^y == -1 (mod n) only for x = -1 (mod n).
%C A274003 See A178751 for further information. In particular, A038192 is the subsequence of odd terms.
%o A274003 (PARI) is_A274003(n)={is_A178751(n) && (bittest(n,0) || !is_A178751(n\2))}
%o A274003 (PARI) select( n -> bittest(n,0) || !setsearch(A178751,n\2), A178751) \\ assuming the vector A178751 holds enough terms of that sequence.
%Y A274003 Cf. A038192, A178751.
%K A274003 nonn,hard,more
%O A274003 1,1
%A A274003 _M. F. Hasler_, Jun 06 2016