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 A261695 #21 May 17 2024 15:24:06 %S A261695 0,4,12,12,36,12,36,60,84,12,36,60,84,108,132,156,180,12,36,60,84,108, %T A261695 132,156,180,204,228,252,276,300,324,348,372,12,36,60,84,108,132,156, %U A261695 180,204,228,252,276,300,324,348,372,396,420,444,468,492,516,540,564,588,612,636,660,684,708,732,756,12,36,60,84,108 %N A261695 First differences of A256534. %C A261695 Number of cells turned ON at n-th stage of cellular automaton of A256534. %C A261695 Similar to A256531 which shares infinitely many terms. %H A261695 N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a> %H A261695 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a> %F A261695 It appears that a(n) = 4 * A241717(n-1), n >= 1. %e A261695 With the positive terms written as an irregular triangle in which the row lengths are the terms of A011782 the sequence begins: %e A261695 4; %e A261695 12; %e A261695 12, 36; %e A261695 12, 36, 60, 84; %e A261695 12, 36, 60, 84, 108, 132, 156, 180; %e A261695 12, 36, 60, 84, 108, 132, 156, 180, 204, 228, 252, 276, 300, 324, 348, 372; %e A261695 ... %o A261695 (GW-BASIC) %o A261695 10 'a261695 First 2^z-1 terms: %o A261695 20 z=6: defdbl a: for i=1 to z: for j=0 to 2^(i-1)-1: n=n+1: a(n)=4^i + 3*(2*j)^2: print a(n)-a(n-1); : next j: next i: end %Y A261695 Cf. A011782, A139251, A147582, A161411, A161415, A241717, A256531, A256534. %K A261695 nonn,tabf %O A261695 0,2 %A A261695 _Omar E. Pol_, Sep 24 2015