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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. Jud McCranie, List of hyperfect numbers. Eric Weisstein's World of Mathematics, Hyperperfect Number. Wikipedia, Hyperperfect number 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: A132184 A143322 A246544 * A287165 A280296 A239920 Adjacent sequences:  A034894 A034895 A034896 * A034898 A034899 A034900 KEYWORD nonn,nice AUTHOR STATUS approved

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Last modified November 16 17:06 EST 2018. Contains 317274 sequences. (Running on oeis4.)