A361515 a(n) = index of first appearance of n in A361511, or -1 if n never appears.

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

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