

A002954


Smallest number such that nth iterate of Chowla function is 0.
(Formerly M1099)


2



2, 4, 8, 15, 12, 27, 24, 36, 90, 96, 245, 288, 368, 676, 1088, 2300, 1596, 1458, 3344, 3888, 5360, 8895, 11852, 25971, 23360, 38895, 35540, 35595, 36032, 53823, 47840, 62055, 59360, 83391, 70784, 128079, 145668, 349299, 254540, 327495, 293744, 328335, 167664
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OFFSET

1,1


COMMENTS

Chowla's function (A048050) = sum of divisors of n except 1 and n.
a(83) > 10^10.  Donovan Johnson, Feb 15 2013


REFERENCES

M. Lal and A. Forbes, A note on Chowla's function, Math. Comp., 25 (1971), 923925.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

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


MATHEMATICA

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 *)


CROSSREFS

Sequence in context: A118897 A098056 A097100 * A019278 A084345 A084561
Adjacent sequences: A002951 A002952 A002953 * A002955 A002956 A002957


KEYWORD

nonn


AUTHOR

N. J. A. Sloane.


EXTENSIONS

Terms 31 to 43 from T. D. Noe, Dec 29 2011


STATUS

approved



