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 A065495 #12 Mar 12 2024 07:59:47 %S A065495 1,2,6,14,32,72,156,336,712,1496,3120,6464,13328,27360,55968,114144, %T A065495 232192,471296,954816,1931264,3900800,7869312,15858432,31928832, %U A065495 64232704,129128960,259431936,520941056,1045557248,2097616896 %N A065495 Number of (binary) bit strings of length n in which an odd length block of 0's is followed by an odd length block of 1's. %H A065495 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,2,-2,-4). %F A065495 G.f.: x^2/((1-2*x)*(1-2*x^2-2*x^3)). %e A065495 a(4) = 6 because of 0100, 0101, 1010, 1101, 0111, 0001. %Y A065495 Cf. A061279 [=2^n - a(n)], A065455, A065494, A065497. %K A065495 nonn,easy %O A065495 2,2 %A A065495 _Len Smiley_, Nov 24 2001