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 A026366 a(n) = a(m) if a(m) has already occurred exactly once and n = a(m)+2m, else a(n) = least positive integer that has not yet occurred. 4
 1, 2, 1, 3, 4, 2, 5, 6, 7, 8, 3, 9, 10, 4, 11, 12, 13, 14, 5, 15, 16, 6, 17, 18, 7, 19, 20, 8, 21, 22, 23, 24, 9, 25, 26, 10, 27, 28, 29, 30, 11, 31, 32, 12, 33, 34, 13, 35, 36, 14, 37, 38, 39, 40, 15, 41, 42, 16, 43, 44, 45, 46, 17, 47, 48, 18, 49 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..67. A. S. Fraenkel, Heap games, numeration systems and sequences, arXiv:math/9809074 [math.CO], 1998; Annals of Combinatorics, 2 (1998), 197-210. J. Shallit, Proof of Irvine's conjecture via mechanized guessing, arXiv preprint arXiv:2310.14252 [math.CO], October 22 2023. MATHEMATICA a[n_] := a[n] = Module[{aa, m}, aa = Array[a, n-1]; For[m = 1, m < n, m++, If[n == a[m] + 2m && Count[aa, a[m]] == 1, Return[a[m]]]]; For[m = 1, True, m++, If[FreeQ[aa, m], Return[m]]]]; a[1] = 1; Array[a, 100] (* Jean-François Alcover, Jan 26 2019 *) CROSSREFS Cf. A026367, A026368. Sequence in context: A166711 A026249 A130527 * A209125 A209137 A269752 Adjacent sequences: A026363 A026364 A026365 * A026367 A026368 A026369 KEYWORD nonn AUTHOR Clark Kimberling EXTENSIONS Description corrected by Aviezri S. Fraenkel STATUS approved

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Last modified April 19 02:12 EDT 2024. Contains 371782 sequences. (Running on oeis4.)