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 A221264 #19 Jul 13 2024 07:05:00
%S A221264 3,6,7,9,11,12,14,18,19,21,22,23,24,27,28,31,33,36,38,42,43,44,46,47,
%T A221264 48,49,54,56,57,59,62,63,66,67,69,71,72,76,77,79,81,83,84,86,88,92,93,
%U A221264 94,96,98,99,103,105,107,108,112,114,118,121,124,126,127,129
%N A221264 Numbers having fewer distinct prime factors of form 4*k+1 than of 4*k+3.
%C A221264 A005089(a(n)) < A005091(a(n)); A005094(a(n)) < 0.
%H A221264 Reinhard Zumkeller, <a href="/A221264/b221264.txt">Table of n, a(n) for n = 1..10000</a>
%o A221264 (Haskell)
%o A221264 a221264 n = a221264_list !! (n-1)
%o A221264 a221264_list = filter ((< 0) . a005094) [1..]
%o A221264 (PARI) is_A221264(n)={#(n=vecsort(factor(n>>valuation(n,2))[,1]%4))&&n[(1+#n)\2]==3} \\ _M. F. Hasler_, Dec 17 2014
%Y A221264 Cf. A005089, A005091, A005094, A078613, A221265.
%K A221264 nonn,easy
%O A221264 1,1
%A A221264 _Reinhard Zumkeller_, Jan 07 2013