A141452 - OEIS

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A141452

a(1)=1, a(n) = the smallest integer > a(n-1) that is divisible by the number of divisors of a(n-1).

1, 2, 4, 6, 8, 12, 18, 24, 32, 36, 45, 48, 50, 54, 56, 64, 70, 72, 84, 96, 108, 120, 128, 136, 144, 150, 156, 168, 176, 180, 198, 204, 216, 224, 228, 240, 260, 264, 272, 280, 288, 306, 312, 320, 322, 328, 336, 340, 348, 360, 384, 400, 405, 410, 416, 420, 432, 440

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OFFSET

1,2

COMMENTS

Odd terms: 1, 45, 405, 1617, 2505, 3645, 5215, 14427, 20745, 24345, 28287, 32475, 40005, 41625, 44145, 46697, 63525, 76185, 78435, 82995, 93645, ..., . - Robert G. Wilson v

LINKS

Table of n, a(n) for n=1..58.

MATHEMATICA

a = {1}; Do[i = a[[ -1]] + 1; While[Mod[i, Length[Divisors[a[[ -1]]]]] > 0, i++ ]; AppendTo[a, i], {60}]; a (* Stefan Steinerberger, Aug 28 2008 *)

a[1] = 1; a[n_] := a[n] = Block[{k = a[n - 1] + 1, d = DivisorSigma[0, a[n - 1]]}, While[ Mod[k, d] != 0, k++ ]; k]; Array[a, 58] (* Robert G. Wilson v *)

CROSSREFS

Sequence in context: A284005 A079212 A354768 * A292854 A330813 A015897

Adjacent sequences: A141449 A141450 A141451 * A141453 A141454 A141455

KEYWORD

nonn

AUTHOR

Leroy Quet, Aug 07 2008

EXTENSIONS

More terms from Robert G. Wilson v, Aug 18 2008 and Stefan Steinerberger, Aug 28 2008

STATUS

approved