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 A309773 n directly precedes a(n) in Sharkovskii ordering. 0
 1, 5, 2, 7, 10, 9, 4, 11, 14, 13, 20, 15, 18, 17, 8, 19, 22, 21, 28, 23, 26, 25, 40, 27, 30, 29, 36, 31, 34, 33, 16, 35, 38, 37, 44, 39, 42, 41, 56, 43, 46, 45, 52, 47, 50, 49, 80, 51, 54, 53, 60, 55, 58, 57, 72, 59, 62, 61, 68, 63, 66, 65, 32, 67, 70, 69, 76 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS Sharkovskii ordering is as follows: - numbers that are not powers of two come first,   ordered by increasing 2-adic valuation and then by increasing value, - powers of two come last, in decreasing order. The number 3 is the least element of Sharkovskii ordering; it is the only number that does not appear in the sequence. The number 1 is the greatest element of Sharkovskii ordering; it does not precede any other number, hence the offset of the sequence is 2. LINKS Wikipedia, Sharkovskii's theorem FORMULA a(2^(k+1)) = 2^k for any k >= 0. a((2*m+1)*2^k) = (2*m+3)*2^k for any m > 0 and k >= 0. PROG (PARI) a(n) = if (hammingweight(n)==1, n/2, my (v=valuation(n, 2)); n+2*2^v) CROSSREFS Cf. A007814. Sequence in context: A155790 A200646 A198130 * A241388 A305574 A248259 Adjacent sequences:  A309770 A309771 A309772 * A309774 A309775 A309776 KEYWORD nonn AUTHOR Rémy Sigrist, Aug 16 2019 STATUS approved

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Last modified September 22 03:54 EDT 2020. Contains 337289 sequences. (Running on oeis4.)