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 A255166 #34 Feb 17 2015 00:14:12 %S A255166 0,1,1,5,1,5,9,21,1,5,9,21,9,29,49,77,1,5,9,21,9,29,49,77,9,29,49,85, %T A255166 57,141,209,261,1,5,9,21,9,29,49,77,9,29,49,85,57,141,209,261,9,29,49, %U A255166 85,57,141,209,269,57,141,217,333,289,597,785,845,1,5,9,21,9,29,49,77,9,29,49,85,57,141,209,261,9,29,49,85 %N A255166 Difference after n generations between the total number of single toothpicks in the I-toothpick structure of A160164 and the total number of ON cells in the "Ulam-Warburton" two-dimensional cellular automaton of A147562. %H A255166 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 A255166 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a> %F A255166 a(n) = A160164(n) - A147562(n). %e A255166 Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins: %e A255166 0; %e A255166 1; %e A255166 1,5; %e A255166 1,5,9,21; %e A255166 1,5,9,21,9,29,49,77; %e A255166 1,5,9,21,9,29,49,77,9,29,49,85,57,141,209,261; %e A255166 1,5,9,21,9,29,49,77,9,29,49,85,57,141,209,261,9,29,49,85,57,141,209,269,57,141,217,333,289,597,785,845; %e A255166 ... %e A255166 It appears that the right border gives [0, 1] together with A126645. The right border gives the largest difference between both C.A. in every period. %e A255166 Also, written the positive terms as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins: %e A255166 1; %e A255166 1; %e A255166 5,1; %e A255166 5,9,21,1; %e A255166 5,9,21,9,29,49,77,1; %e A255166 5,9,21,9,29,49,77,9,29,49,85,57,141,209,261,1; %e A255166 5,9,21,9,29,49,77,9,29,49,85,57,141,209,261,9,29,49,85,57,141,209,269,57,141,217,333,289,597,785,845,1; %e A255166 ... %e A255166 The right border gives A000012 according with the illustrations as shown below. In this triangle the right border gives the smallest difference between both C.A. in every period. %e A255166 For example: after 8 generations the structures look like this: %e A255166 . %e A255166 . O %e A255166 . O O O %e A255166 . O O O %e A255166 . _ _ _ _ _ _ _ _ O O O O O O O %e A255166 . |_ _| |_ _| O O O O O %e A255166 . | |_|_ _|_| | O O O O O O O O O %e A255166 |_|_|_ _|_|_| O O O O O O O %e A255166 . | | | | | O O O O O O O O O O O O O O O %e A255166 . |_ _|_|_|_ _| O O O O O O O %e A255166 . | |_|_ _|_| | O O O O O O O O O %e A255166 . |_|_| |_|_| O O O O O %e A255166 . _|_ _|_ _|_ _|_ O O O O O O O %e A255166 . O O O %e A255166 . 86 toothpicks O O O %e A255166 . O %e A255166 . %e A255166 . 85 ON cells %e A255166 . %e A255166 a(8) = 1 because the I-toothpick structure contains 86 single toothpicks and the "Ulam-Warburton" two-dimensional cellular automaton has 85 ON cells, so the difference of the number of elements between both structures is equal to 86 - 85 = 1. %Y A255166 Cf. A126645, A139250, A147562, A160164, A169707, A170903. %K A255166 nonn,tabf %O A255166 0,4 %A A255166 _Omar E. Pol_, Feb 15 2015