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A002954 Smallest number such that n-th 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 (list; graph; refs; listen; history; text; internal format)
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), 923-925.

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

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Last modified October 26 01:20 EDT 2014. Contains 248566 sequences.