A328860 4-imperfect numbers.

993803899780063855042560, 2028353759451110328141864960, 6476620014866676143312363520, 387181686948544515909353472000, 2649915489117854125448118558720, 13218781450342886008500533944320, 116541687771511899288715395072000, 140546952362321659275095310336000, 790237823061979356970990436352000, 1008608294500958463943865794560000

Offset

1,1

Links

Max Alekseyev, Table of n, a(n) for n = 1..1613

Douglas E. Iannucci, On a variation of perfect numbers, INTEGERS: Electronic Journal of Combinatorial Number Theory, 6 (2006), #A41.

Andrew Lelechenko, 4-imperfect numbers, Apr 19 2014.

Michel Marcus, More 4-imperfect numbers, Nov 07 2017.

Michel Marcus, solveIMP PARI script

Michel Marcus, List of 4-imperfect numbers (including the 2 files above), last edit Jun 2019.

Weiyi Zhou and Long Zhu, On k-imperfect numbers, INTEGERS: Electronic Journal of Combinatorial Number Theory, 9 (2009), #A01.

Prog

(PARI) solveIMP(1, 4, 10^24)

Crossrefs

Cf. A127724 (k-imperfect), A127725 (2-imperfect), A127726 (3-imperfect).

Cf. A309806 (the k values).

Cf. A206369 (the rho function).

Sequence in context: A003806 A257374 A217422 * A377422 A095442 A332605

Adjacent sequences: A328857 A328858 A328859 * A328861 A328862 A328863

Keyword

nonn

Author

Michel Marcus, Feb 16 2020

Extensions

Terms a(4) onward from Max Alekseyev, Oct 21 2025

Status

approved