A362135 Indices of novel terms in A360179.

1, 3, 5, 7, 9, 12, 15, 17, 21, 25, 29, 31, 36, 41, 47, 52, 58, 64, 69, 74, 82, 87, 92, 100, 106, 112, 120, 128, 138, 145, 153, 160, 168, 176, 183, 189, 198, 209, 220, 233, 242, 252, 265, 277, 285, 294, 309, 325, 338, 349, 359, 371, 384, 400, 413, 430, 447, 459, 474, 492, 515, 533, 545, 557, 570, 594

Offset: 1

Author

Michael De Vlieger, Apr 10 2023

Keywords

• nonn

Comments

If we read A360179 as an irregular triangle of rows whose terms strictly increase, then a(n) is the index k such that A360179(k) is the last and largest term in row n.

A362128 is a subsequence of this sequence.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..58188

Crossrefs

Cf. A360179, A362128, A362134.

Programs

Mathematica

nn = 600;
c[] := False; h[] := 0; f[n_] := DivisorSigma[0, n];
a[1] = j = u = w = 1;
{1}~Join~Rest@ Reap[Do[
      If[c[j],
        k = j + f[u]; h[j]++; h[u]--,
        k = f[j]; c[j] = True; h[j]++; Sow[n - 1] ];
      u = Min[u, j]; Set[{a[n], q[k], j}, {k, True, k}];
      While[h[u] == 0, u++], {n, 2, nn}] ][[-1, -1]]