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A034897 Hyperperfect numbers. 9
6, 21, 28, 301, 325, 496, 697, 1333, 1909, 2041, 2133, 3901, 8128, 10693, 16513, 19521, 24601, 26977, 51301, 96361, 130153, 159841, 163201, 176661, 214273, 250321, 275833, 296341, 306181, 389593, 486877, 495529, 542413, 808861, 1005421, 1005649, 1055833 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, Sect. B2.

J. Roberts, Lure of the Integers, see Integer 28, p. 177.

LINKS

Jud McCranie and Donovan Johnson, Table of n, a(n) for n = 1..10000 (first 2190 terms from Jud McCranie)

J. S. McCranie, A study of hyperperfect numbers, J. Int. Seqs. Vol. 3 (2000) #P00.1.3

Eric Weisstein's World of Mathematics, Hyperperfect Number.

Wikipedia, Hyperperfect number

Jud McCranie, List of hyperfect numbers.

MATHEMATICA

hpnQ[n_]:=Module[{c=DivisorSigma[1, n]-n-1}, c>0&&IntegerQ[(n-1)/c]]; Select[Range[2, 809000], hpnQ] (* Harvey P. Dale, Jan 17 2012 *)

CROSSREFS

Cf. A034898, A007592, A019279.

Sequence in context: A046467 A132184 A143322 * A239920 A173622 A064440

Adjacent sequences:  A034894 A034895 A034896 * A034898 A034899 A034900

KEYWORD

nonn,nice,changed

AUTHOR

Jud McCranie

STATUS

approved

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Last modified April 24 19:08 EDT 2014. Contains 240988 sequences.