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 A194434 D-toothpick sequence of the second kind starting with a X-shaped cross formed by 4 D-toothpicks. 8
 0, 4, 12, 28, 44, 60, 92, 136, 168, 184, 216, 280, 376, 424, 504, 604, 668, 684, 716, 780, 876, 988, 1132, 1300, 1476, 1556, 1652, 1812, 2068, 2196, 2372, 2584, 2712, 2728, 2760, 2824, 2920, 3032, 3176, 3352, 3560, 3728, 3920, 4160, 4560, 4832, 5168 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS On the infinite square grid we start with no toothpicks. At stage 1, we place a cross as a "X", formed by 4 D-toothpicks of length sqrt(2) and centered at the origin. At stage 2, we place 8 toothpicks of length 1. At stage 3, we place 16 D-toothpicks of length sqrt(2). And so on. The sequence gives the number of toothpicks and D-toothpicks in the structure after n-th stage. The first differences (A194435) give the number of toothpicks or D-toothpicks added at n-th stage. Apparently this cellular automaton has a fractal behavior (or like-fractal behavior) related to power of 2, similar to A194270 and very similar to A194432. The octagonal structure contains a large number of distinct closed polygonal regions. For more information see A194270, A194440 and A194442. First differs from A220514 at a(13). - Omar E. Pol, Mar 23 2013 LINKS N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS FORMULA a(n) = 4*A194444(n). CROSSREFS Cf. A139250, A194270, A194432, A194435, A194440, A194442, A194444, A212008, A220514. Sequence in context: A009906 A194432 A220512 * A220514 A301005 A178571 Adjacent sequences:  A194431 A194432 A194433 * A194435 A194436 A194437 KEYWORD nonn AUTHOR Omar E. Pol, Sep 03 2011 EXTENSIONS More terms from Omar E. Pol, Mar 23 2013 STATUS approved

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Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)