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 A361515 a(n) = index of first appearance of n in A361511, or -1 if n never appears. 2
 1, 3, 5, 7, 9, 12, 14, 18, 25, 28, 21, 42, 32, 80, 39, 71, 47, 77, 53, 100, 59, 115, 88, 67, 147, 120, 106, 128, 94, 154, 187, 142, 178, 161, 134, 170, 226, 205, 246, 327, 287, 217, 313, 196, 236, 334, 506, 348, 266, 302, 256, 359, 406, 374, 481, 416, 471, 383, 431, 280 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Conjecture: This is a permutation of the positive integers. LINKS Michael De Vlieger, Table of n, a(n) for n = 1..17878 (All terms that appear in a(n) for n = 1..2^24) MATHEMATICA nn = 1000; c[_] = False; q[_] = 0; f[n_] := DivisorSigma[0, n]; a[1] = m = 1; Do[(If[c[#], a[n] = # + f[a[m]] ; m++, a[n] = f[#] ]; c[#] = True; If[q[#] == 0, q[#] = n - 1]) &[a[n - 1]], {n, 2, nn}]; TakeWhile[Array[q, nn], # > 0 &] (* Michael De Vlieger, Apr 08 2023 *) CROSSREFS Cf. A361511-A361514. Sequence in context: A186705 A361512 A361516 * A072154 A309269 A362135 Adjacent sequences: A361512 A361513 A361514 * A361516 A361517 A361518 KEYWORD nonn AUTHOR N. J. A. Sloane, Apr 08 2023 STATUS approved

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Last modified May 28 15:12 EDT 2024. Contains 372916 sequences. (Running on oeis4.)