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 A159795 a(n) = 4*A153006(n). 6
 0, 4, 12, 24, 36, 52, 80, 112, 132, 148, 176, 212, 252, 312, 400, 480, 516, 532, 560, 596, 636, 696, 784, 868, 924, 984, 1076, 1188, 1328, 1536, 1792, 1984, 2052, 2068, 2096, 2132, 2172, 2232, 2320, 2404, 2460, 2520, 2612, 2724, 2864, 3072, 3328, 3524, 3612 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS For the first differences see A147646. [From Omar E. Pol, Jul 24 2009] It appears that a(n) is also the total path length of a toothpick structure as A139250 after n-th stage which is constructed following a special rule: toothpicks of the new generation have length 4 when are placed on the square grid (note that every toothpick has four components of length 1), but after every stage, one (or two) of the four components of every toothpick of the new generation is removed, if such component contains a endpoint of the toothpick and if such endpoint is touching the midpoint or the endpoint of another toothpick. The truncated endpoints of the toothpicks remain exposed for ever. Note that there are three sizes of toothpicks in the structure: toothpicks of length 4, 3 and 2. a(n) is also the total number of components in the structure after n-th stage. a(n) is also the number of grid points that are covered after n-th stage, except the central point of the structure. The toothpick sequence A139250 gives the number of toothpicks after n-th stage. - Omar E. Pol, Oct 24 2011 LINKS David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS CROSSREFS Cf. A139250, A139251, A152980, A153006, A159793, A159794. Cf. A147646, A152980. [From Omar E. Pol, Jul 24 2009] Sequence in context: A297568 A071228 A108997 * A033602 A008122 A008103 Adjacent sequences:  A159792 A159793 A159794 * A159796 A159797 A159798 KEYWORD nonn AUTHOR Omar E. Pol, May 02 2009 EXTENSIONS More terms from Omar E. Pol, Jul 24 2009 STATUS approved

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Last modified February 19 20:48 EST 2018. Contains 299357 sequences. (Running on oeis4.)