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Search: id:A002975
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| A002975 |
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Primitive weird numbers.
(Formerly M5340)
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+0
2
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| 70, 836, 4030, 5830, 7192, 7912, 9272, 10792, 17272, 45356, 73616, 83312, 91388, 113072, 243892, 254012, 338572, 343876, 388076, 519712, 539744, 555616, 682592, 786208, 1188256, 1229152, 1713592, 1901728, 2081824, 2189024, 3963968, 4128448
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
S. J. Benkoski and P. Erdos, On weird and pseudoperfect numbers, Math. Comp., 28 (1974), 617-623.
R. K. Guy, Unsolved Problems in Number Theory, B2.
R. Honsberger, Mathematical Gems, M.A.A., 1973, p. 113.
Problem E2308, Amer. Math. Monthly, 79 (1972), 774.
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LINKS
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Robert G. Wilson v, Table of n, a(n) for n = 1..57 . [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 04 2009]
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MATHEMATICA
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(* first do *) << Combinatorica` (* then *) fQ[n_] := Block[{d = Most@ Divisors@ n, l = 2^(DivisorSigma[0, n] - 1), i = 1}, i = 1; While[i < l && Plus @@ NthSubset[i, d] != n, i++ ]; i == l]; lst = {}; Do[m = n; If[ Mod[n, 6] != 0 && DivisorSigma[1, n] > 2 n && Union[ Mod[ n, Join[lst, {n + 1}]]][[1]] != 0 && fQ@n, AppendTo[lst, n]; Print@n], {n, 2, 42000000, 2}] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 04 2009]
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CROSSREFS
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Cf. A006037.
Sequence in context: A104475 A027804 A006037 this_sequence A061170 A125114 A061606
Adjacent sequences: A002972 A002973 A002974 this_sequence A002976 A002977 A002978
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Jud McCranie (j.mccranie(AT)comcast.net), Oct 21 2001
Added one more term. Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 04 2009
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