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 A220514 #18 Feb 22 2023 18:27:17 %S A220514 0,4,12,28,44,60,92,136,168,184,216,280,376,440,520,620,684,700,732, %T A220514 796,892,1020,1164,1332,1508,1588,1684,1860,2116,2276,2452,2664,2792, %U A220514 2808,2840,2904,3000,3128,3272,3448,3656,3824,4016,4272,4676,4992 %N A220514 D-toothpick sequence of the third kind starting with a X-shaped cross formed by 4 D-toothpicks. %C A220514 This is a toothpick sequence of forking paths to 135 degrees. The sequence gives the number of toothpicks and D-toothpicks in the structure after n-th stage. A221528 (the first differences) give the number of toothpicks or D-toothpicks added at n-th stage. It appears that the structure has a fractal (or fractal-like) behavior. For more information see A194700. %C A220514 First differs from A194434 at a(13). %H A220514 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 A220514 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a> %F A220514 a(n) = 4*A220524(n). %Y A220514 Cf. A139250, A194270, A194700, A194434, A220500, A220520, A220522, A221528. %K A220514 nonn %O A220514 0,2 %A A220514 _Omar E. Pol_, Dec 15 2012