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 A127260 #10 Aug 12 2015 21:19:47
%S A127260 0,1,3,4,6,7,8,10,13,15,16,18,19,20,21,22,23,25,26,27,28,31,33,34,36,
%T A127260 37,38,40,41,43,45,46,47,48,49,52,53,55,58,59,60,61,62,63,64,66,67,68,
%U A127260 69,70,73,76,78,79,81,82,83,85,86,87,88,89,90,91,92,93,94,97,98,99,100,102
%N A127260 Indices n of odd numbers of the form 8*n+1 that are not primes.
%C A127260 Could be generated from A045751 by removing all odd terms there, then halving each remaining term. - _R. J. Mathar_, Jun 08 2007
%p A127260 isA127260 := proc(n) not isprime(8*n+1) ; end: for n from 0 to 200 do if isA127260(n) then printf("%d, ",n) ; fi ; od ; # _R. J. Mathar_, Jun 08 2007
%t A127260 a = Flatten[Table[If[PrimeQ[8*n + 1] == False, n, {}], {n, 0, 50}]]
%Y A127260 Cf. A045751.
%K A127260 nonn
%O A127260 1,3
%A A127260 _Roger L. Bagula_, May 17 2007
%E A127260 More terms from _R. J. Mathar_, Jun 08 2007