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

1,2

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

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]]

Crossrefs

Cf. A360179, A362128, A362134.

Sequence in context: A361515 A072154 A309269 * A204206 A080751 A025218

Adjacent sequences: A362132 A362133 A362134 * A362136 A362137 A362138

Keyword

nonn

Author

Michael De Vlieger, Apr 10 2023

Status

approved