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A175876
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Numbers n such that sigma(n+2) = 2*sigma(n).
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4
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118, 1558, 2938, 17758, 19918, 32218, 33838, 55963, 71038, 186778, 308038, 511498, 523774, 553498, 699358, 838213, 1048903, 1159378, 1328938, 1333246, 1700038, 2462686, 2703886, 2956078, 3115318, 3561094, 3764206, 3972694, 7625878, 7852918, 8048962
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OFFSET
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1,1
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COMMENTS
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a(1) = A175874(2).
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LINKS
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Vincenzo Librandi and Donovan Johnson, Table of n, a(n) for n = 1..1000 (first 171 terms from Vincenzo Librandi)
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MAPLE
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with(numtheory); A175876:=proc(q) local n;
for n from 2 to q do if sigma(n+2)=2*sigma(n) then print(n); fi; od; end:
A175876 (10^10); # Paolo P. Lava, Apr 04 2013
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MATHEMATICA
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Do[If[DivisorSigma[1, n+2]==2 DivisorSigma[1, n], Print[n]], {n, 2, 10^7}] (* or *) Select[Range[8000000], DivisorSigma[1, # + 2] == 2 DivisorSigma[1, #]&](* Vincenzo Librandi, Apr 04 2013 *)
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CROSSREFS
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Cf. A000203, A002961, A175874, A175875.
Sequence in context: A250793 A334646 A232776 * A220715 A230917 A230248
Adjacent sequences: A175873 A175874 A175875 * A175877 A175878 A175879
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov, Oct 06 2010
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STATUS
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approved
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