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A067064 Numbers n such that sigma(sigma(sigma(n)))) == 0 (mod sigma(n)). 1
1, 3, 7, 8, 14, 15, 20, 23, 24, 26, 38, 41, 44, 59, 60, 65, 78, 83, 92, 114, 123, 132, 133, 135, 140, 143, 158, 167, 168, 177, 182, 188, 195, 203, 204, 209, 220, 224, 239, 246, 248, 249, 266, 284, 285, 286, 287, 297, 299, 334, 378, 381, 395, 413, 415, 420, 437 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[500], Divisible[DivisorSigma[1, DivisorSigma[1, DivisorSigma[ 1, #]]], DivisorSigma[ 1, #]]&] (* Harvey P. Dale, Oct 04 2017 *)

PROG

(PARI) { n=0; for (m=1, 10^10, if (sigma(sigma(sigma(m))) % sigma(m) == 0, write("b067064.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, May 02 2010

CROSSREFS

Sequence in context: A279517 A106474 A127441 * A093722 A309745 A002381

Adjacent sequences:  A067061 A067062 A067063 * A067065 A067066 A067067

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Feb 17 2002

STATUS

approved

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Last modified December 5 20:45 EST 2019. Contains 329779 sequences. (Running on oeis4.)