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

Author

N. J. A. Sloane, Apr 08 2023

Keywords

• nonn

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)

Crossrefs

Cf. A361511-A361514.

Programs

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 *)