A362135 - OEIS

%I #8 Apr 14 2023 11:35:46

%S 1,3,5,7,9,12,15,17,21,25,29,31,36,41,47,52,58,64,69,74,82,87,92,100,

%T 106,112,120,128,138,145,153,160,168,176,183,189,198,209,220,233,242,

%U 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

%N Indices of novel terms in A360179.

%C 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.

%C A362128 is a subsequence of this sequence.

%H Michael De Vlieger, <a href="/A362135/b362135.txt">Table of n, a(n) for n = 1..58188</a>

%t nn = 600;

%t c[_] := False; h[_] := 0; f[n_] := DivisorSigma[0, n];

%t a[1] = j = u = w = 1;

%t {1}~Join~Rest@ Reap[Do[

%t       If[c[j],

%t         k = j + f[u]; h[j]++; h[u]--,

%t         k = f[j]; c[j] = True; h[j]++; Sow[n - 1] ];

%t       u = Min[u, j]; Set[{a[n], q[k], j}, {k, True, k}];

%t       While[h[u] == 0, u++], {n, 2, nn}] ][[-1, -1]]

%Y Cf. A360179, A362128, A362134.

%K nonn

%O 1,2

%A _Michael De Vlieger_, Apr 10 2023