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A237286 Numbers n such that sigma(n) - n = perfect number (A000396). 1
6, 25, 28, 496, 652, 8128, 10682, 10828, 33550336, 44655764, 8589869056, 8623554304, 137438691328 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that sum of the proper divisors of n (A001065) = perfect number (A000396).

Supersequence of perfect numbers (A000396).

a(14) > 10^12. - Giovanni Resta, Mar 01 2014

Up to a(13), note that the terms that are not perfect are deficient. - Michel Marcus, Mar 12 2014

LINKS

Table of n, a(n) for n=1..13.

EXAMPLE

Number 25 is a term because sigma(25) - 25 = 31 - 25 = 6 (perfect number).

PROG

(PARI) isok(n) = sigma(smn=sigma(n) - n) == 2*smn; \\ Michel Marcus, Mar 01 2014

CROSSREFS

Cf. A000203 (sigma(n)).

Sequence in context: A136606 A074096 A126016 * A046416 A042879 A042495

Adjacent sequences:  A237283 A237284 A237285 * A237287 A237288 A237289

KEYWORD

nonn,more

AUTHOR

Jaroslav Krizek, Feb 28 2014

EXTENSIONS

a(10) from Michel Marcus, Mar 01 2014

a(11)-a(13) from Giovanni Resta, Mar 01 2014

STATUS

approved

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Last modified July 23 11:44 EDT 2019. Contains 325254 sequences. (Running on oeis4.)