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A293992 Numbers n such that sigma(n)-n-1 is a perfect number. 0
8, 115, 187, 1375, 2455, 8143, 13543, 18261, 21103, 23479, 40615, 41623, 43279, 49183, 49441, 51703, 56743, 61063, 61279, 61423, 89287, 95551, 137887, 214303, 331567, 379807, 476071, 715471, 1422871, 1515967, 1793527, 1977127, 2431087, 3098527, 3663871 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..35.

FORMULA

Numbers n such that sigma(n)-n-1 is a perfect number.

EXAMPLE

For n=8 it is sigma(8)-8-1=6; for n=115 it is sigma(115)-115-1=28

MATHEMATICA

With[{pn=PerfectNumber[Range[10]]}, Select[Range[37*10^5], MemberQ[pn, DivisorSigma[ 1, #]-#-1]&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Feb 04 2019 *)

CROSSREFS

Sequence in context: A220635 A113670 A156468 * A220575 A240890 A241105

Adjacent sequences:  A293989 A293990 A293991 * A293993 A293994 A293995

KEYWORD

nonn

AUTHOR

Zdenek Cervenka, Oct 21 2017

STATUS

approved

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Last modified June 16 14:16 EDT 2021. Contains 345057 sequences. (Running on oeis4.)