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 A091461 #13 Sep 14 2020 00:34:39
%S A091461 0,3,2,6,12,75,44,92,184,1208,1256,4840,4792,36055,9912,19832,39664,
%T A091461 563952,576464,4496112,4499184
%N A091461 Smallest number containing in its binary representation substrings forming an arithmetic progression exactly of size n.
%C A091461 A091460(a(n))=n and A091460(m)<>n for m<a(n).
%e A091461 a(7) = 44->'101100', {0+k*1: 0<=k<7}: bbbbb0 => 1bbbbb => 10bbbb => bb11bb => bbb100 => 101bbb => bb110b.
%e A091461 a(6) > 44: Although there is an arithmetic progression of length 6 in the binary expansion of 44, it is extendable (to length 7).
%K A091461 nonn,base
%O A091461 1,2
%A A091461 _Reinhard Zumkeller_, Jan 12 2004
%E A091461 a(12)-a(13) by _Álvar Ibeas_, Sep 09 2020
%E A091461 a(14)-a(21) by _Álvar Ibeas_, Sep 12 2020