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Search: id:A053781
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| A053781 |
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Numbers n such that n divides sum of first n composite numbers. |
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+0
4
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| 1, 2, 3, 7, 11, 71, 107, 115, 139, 155, 681, 1671, 4876, 21464, 30046, 311271, 788749, 10893662, 20743270, 134568163, 163879554, 920161004, 6364787032, 21400458779, 47934932406, 56133884369
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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When n | A053767(n). - Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 24 2004
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MATHEMATICA
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c = s = 0; Do[ If[ !PrimeQ[n], c++; s = s + n; If[ Mod[s, c] == 0, Print[c]]], {n, 2, 10^9}] (from Robert G. Wilson v Nov 23 2004)
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CROSSREFS
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Cf. A002808.
Sequence in context: A056292 A106125 A073609 this_sequence A066749 A046480 A137767
Adjacent sequences: A053778 A053779 A053780 this_sequence A053782 A053783 A053784
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KEYWORD
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more,nonn
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AUTHOR
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G. L. Honaker, Jr. (honak3r(AT)gmail.com), Mar 29 2000
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EXTENSIONS
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a(19), a(20), a(21) & a(22) from Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 24 2004
a(23), a(24), a(25) & a(26) from Sean A. Irvine (sairvin(AT)xtra.co.nz), Oct 01 2009
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