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A195864 Numbers n such that sigma(n) + tau(n) is a perfect number (A000396). 0
3, 14, 15, 168, 326, 5414, 33357341, 4324809536 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A002093(848) < a(9) <= 1155321467378283328. - Donovan Johnson, Nov 03 2011

LINKS

Table of n, a(n) for n=1..8.

MATHEMATICA

perfect = {6, 28, 496, 8128, 33550336, 8589869056, 137438691328}; Select[Range[10000], MemberQ[perfect, DivisorSigma[0, #] + DivisorSigma[1, #]] &] (* T. D. Noe, Nov 03 2011 *)

CROSSREFS

Cf. A007503 (sigma(n) + tau(n)).

Sequence in context: A037244 A016062 A009401 * A022890 A032920 A134767

Adjacent sequences:  A195861 A195862 A195863 * A195865 A195866 A195867

KEYWORD

nonn

AUTHOR

Jeff Kruse, Oct 26 2011

EXTENSIONS

a(8) from Donovan Johnson, Nov 03 2011

STATUS

approved

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Last modified December 4 05:56 EST 2021. Contains 349470 sequences. (Running on oeis4.)