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 A117592 a(n)=a(3n)=a(3n+1)=a(3n+2)/2 with a(0)=1. 9
 1, 1, 2, 1, 1, 2, 2, 2, 4, 1, 1, 2, 1, 1, 2, 2, 2, 4, 2, 2, 4, 2, 2, 4, 4, 4, 8, 1, 1, 2, 1, 1, 2, 2, 2, 4, 1, 1, 2, 1, 1, 2, 2, 2, 4, 2, 2, 4, 2, 2, 4, 4, 4, 8, 2, 2, 4, 2, 2, 4, 4, 4, 8, 2, 2, 4, 2, 2, 4, 4, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Row sums of number triangle A117944. Product of the nonzero digits of (n written in base 3). - Ilya Gutkovskiy, Nov 15 2020 a(n) = 1, 2, 4, 8, 16, 32, 64 iff n is respectively in A005836, A023699, A023700, A023701, A023702, A023703, A023704. - Bernard Schott, Dec 04 2020 LINKS Felix FrÃ¶hlich, Table of n, a(n) for n = 0..10000 (first 2001 terms from Vincenzo Librandi) FORMULA a(n) = a(3n)/a(0) = a(3n+1)/a(1) = a(3n+2)/a(2). a(n) = abs(A117942(n)). G.f. A(x) satisfies: A(x) = (1 + x + 2*x^2) * A(x^3). - Ilya Gutkovskiy, Nov 15 2020 a(n) = 2^A081603(n). - Kevin Ryde, Nov 15 2020 MATHEMATICA Nest[ Join[#, #, 2#] &, {1}, 5] (* Robert G. Wilson v, Jul 27 2014 *) PROG (PARI) a(n) = 1 << hammingweight(digits(n, 3)>>1); \\ Kevin Ryde, Nov 15 2020 CROSSREFS See A338882 for similar sequences. Cf. A081603 (log2), A117942 (signed), A117944. Cf. A005836, A023699, A023700, A023701, A023702, A023703, A023704. Sequence in context: A133098 A145788 A323861 * A117942 A290092 A066877 Adjacent sequences:  A117589 A117590 A117591 * A117593 A117594 A117595 KEYWORD nonn,base AUTHOR Paul Barry, Apr 05 2006 EXTENSIONS Added a(0) = 1 in the Name by Bernard Schott, Dec 04 2020 STATUS approved

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Last modified April 17 02:26 EDT 2021. Contains 343059 sequences. (Running on oeis4.)