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 A220524 #20 Feb 22 2023 15:03:33 %S A220524 0,1,3,7,11,15,23,34,42,46,54,70,94,110,130,155,171,175,183,199,223, %T A220524 255,291,333,377,397,421,465,529,569,613,666,698,702,710,726,750,782, %U A220524 818,862,914,956,1004,1068,1168,1248,1332,1423,1507,1535,1559,1607 %N A220524 D-toothpick sequence of the third kind in the first quadrant. %C A220524 This is a toothpick sequence of forking paths to 135 degrees in the first quadrant. The sequence gives the number of toothpicks and D-toothpicks in the structure after n-th stage. A220525 (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 A220524 First differs from A194444 at a(13). %H A220524 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 A220524 <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a> %F A220524 a(n) = A220514(n)/4. - _Omar E. Pol_, Mar 23 2013 %Y A220524 Cf. A139250, A194270, A194700, A194444, A220500, A220514, A220520, A220525. %K A220524 nonn %O A220524 0,3 %A A220524 _Omar E. Pol_, Dec 15 2012