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 A160409 #6 Feb 24 2021 02:48:18 %S A160409 1,1,2,4,4,4,4,4,8,16,16,8,4,4,8 %N A160409 First differences of toothpick numbers A160408. %C A160409 Number of toothpick added to the toothpick pyramid at the round n. %C A160409 See also the toothpick sequences A139250, A160160 and the toothpick triangle A160406. %H A160409 David Applegate, Omar E. Pol and N. J. A. Sloane, <a href="/A000695/a000695_1.pdf">The Toothpick Sequence and Other Sequences from Cellular Automata</a>, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.] %H A160409 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> %e A160409 Contribution from _Omar E. Pol_, Jun 06 2009: (Start) %e A160409 Array begins: %e A160409 ======== %e A160409 x, y, z %e A160409 ======== %e A160409 1, 1, 2; %e A160409 4, 4, 4; %e A160409 4, 4, 8; %e A160409 16, 16, 8; %e A160409 4, 4, 8; %e A160409 (End) %Y A160409 Cf. A139250, A139251, A160160, A160161, A160406, A160407, A160408. %K A160409 more,nonn %O A160409 1,3 %A A160409 _Omar E. Pol_, May 23 2009 %E A160409 More terms from _Omar E. Pol_, Jun 06 2009