1,1

Chowla's function (A048050) = sum of divisors of n except 1 and n.

a(83) > 10^10. - Donovan Johnson, Feb 15 2013

The first 35 terms were found by Lal and Forbes (1971). - Amiram Eldar, Mar 09 2024

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Donovan Johnson, Table of n, a(n) for n = 1..82

M. Lal and A. Forbes, A note on Chowla's function, Math. Comp., 25 (1971), 923-925.

chowla[n_] := DivisorSigma[1, n] - 1 - n; chowlaSeq[n_] := Module[{m = n, cnt = 0, seq = {}}, While[m > 0 && ! MemberQ[seq, m], AppendTo[seq, m]; m = chowla[m]; cnt++]; If[m == 0, AppendTo[seq, m]]; seq]; nn = 20; t = Table[0, {nn}]; left = nn; n = 1; While[left > 0, n++; cSeq = chowlaSeq[n]; c = Length[cSeq] - 1; If[cSeq[[-1]] == 0 && c <= nn && t[[c]] == 0, t[[c]] = n; left--]]; t (* T. D. Noe, Dec 29 2011 *)

Cf. A048050.

Sequence in context: A118897 A098056 A097100 * A019278 A267894 A384500

Adjacent sequences: A002951 A002952 A002953 * A002955 A002956 A002957

a(31)-a(43) from T. D. Noe, Dec 29 2011

approved