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A072815
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Sum of proper divisors of 6n + 1.
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1
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0, 1, 1, 1, 6, 1, 1, 1, 8, 17, 1, 1, 1, 1, 23, 21, 1, 1, 1, 29, 12, 1, 27, 1, 35, 1, 1, 1, 14, 73, 1, 29, 1, 1, 47, 1, 39, 1, 1, 53, 1, 33, 35, 45, 59, 1, 1, 1, 18, 65, 51, 1, 1, 41, 109, 1, 1, 57, 1, 77, 20, 1, 1, 1, 191, 41, 1, 45, 1, 89, 1, 69, 1, 1, 95, 53, 1
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OFFSET
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0,5
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COMMENTS
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the square root of t(n) < s(t(4n-1, 4n-2, 4n-3, 4n-4)) < s(t(4n)).
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LINKS
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T. D. Noe, Table of n, a(n) for n = 0..1000
Eric Weisstein's World of Mathematics, Perfect Numbers
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FORMULA
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s(t(n)), where t(n)=6n + 1 and s(n) is the restricted divisor function.
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EXAMPLE
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a(1) = s(t(1))=1 since t(1)=7 and s(7)=1 under the definition of the restricted divisor function.
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MATHEMATICA
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Table[c=6n+1; DivisorSigma[1, c]-c, {n, 0, 80}] (* Harvey P. Dale, Nov 13 2013 *)
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CROSSREFS
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Sequence in context: A034460 A063919 A308135 * A348979 A080304 A340677
Adjacent sequences: A072812 A072813 A072814 * A072816 A072817 A072818
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KEYWORD
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nonn
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AUTHOR
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Hisanobu Shinya (ilikemathematics(AT)hotmail.com), Jul 14 2002
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EXTENSIONS
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Corrected by Harvey P. Dale, Nov 13 2013
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STATUS
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approved
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