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 A222177 #16 Mar 24 2013 13:51:07 %S A222177 0,1,2,2,2,4,6,4,2,4,8,8,6,10,14,8,2,4,8,12,16 %N A222177 Number of pentagons added at n-th stage to the structure of A222176. %C A222177 Essentially the first differences of A222176. %C A222177 Also number of P-toothpicks added at n-th stage to the P-toothpick structure of A222176. %C A222177 First differs from A152968 at a(10). %H A222177 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 A222177 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a> %F A222177 a(n) = A222181(n+1)/5, n >= 1. %e A222177 Apparently this is an irregular triangle: %e A222177 0; %e A222177 1; %e A222177 2, 2; %e A222177 2, 4, 6, 4; %e A222177 2, 4, 8, 8, 6, 10, 14, 8; %e A222177 2, 4, 8, 12, 16,... %Y A222177 Cf. A139251, A152968, A222173, A222176, A222180, A222181. %K A222177 nonn,tabf,more %O A222177 0,3 %A A222177 _Omar E. Pol_, Mar 21 2013