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A049603 (1+e)-sigma perfect numbers: (1+e)-sigma(x)=2*x. 3
6, 28, 264, 1104, 3360, 75840, 6499584, 151062912, 2171581440, 4686409728, 316023611904 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The function (1+e)-sigma(n) is defined in A051378. This sequence lists solutions to A051378(n) = 2*n.

a(12) > 10^12. - Giovanni Resta, Jun 12 2016

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

Factorizations: 2*3, 2^2*7, 2^3*3*11, 2^4*3*23, 2^5*3*5*7, 2^6*3*5*79, 2^8*3^2*7*13*31, 2^7*3^2*7*11*13*131, 2^10*3*5*7*19*1063

MATHEMATICA

(* Assuming all terms greater than 28 are multiple of 24 *) ok[n_] := 2*n == Times @@ (1 + Sum[First[#]^s, {s, Divisors[Last[#]]}] & ) /@ FactorInteger[n]; Reap[For[n = 2, n <= 2171581440, n = n + If[n < 48, 1, 24], If[ok[n], Print[n]; Sow[n]]]][[2, 1]] (* Jean-François Alcover, Jun 26 2012 *)

CROSSREFS

Cf. A049599, A051378.

Sequence in context: A090898 A134872 A281003 * A035527 A220437 A173360

Adjacent sequences:  A049600 A049601 A049602 * A049604 A049605 A049606

KEYWORD

nonn,nice

AUTHOR

Yasutoshi Kohmoto

EXTENSIONS

151062912 inserted by Jean-François Alcover, Jun 26 2012

a(10)-a(11) from Giovanni Resta, Jun 12 2016

STATUS

approved

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Last modified February 17 02:33 EST 2019. Contains 320200 sequences. (Running on oeis4.)