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Search: id:A116906
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| A116906 |
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Sum of squares of divisors of n!. |
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+0
1
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| 1, 1, 5, 50, 850, 22100, 806806, 40340300, 2584263500, 209609328500, 20993420690550, 2561197324247100, 368819285671473000, 62699278564150410000, 12294076739210974071000, 2766341857504878226501200
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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See also A062569 sigma_1(n!).
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FORMULA
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a(n) = A001157(A000142(n)). a(n) = Sum[d|n! ] d^2. a(n) = sigma_2(n!).
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EXAMPLE
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a(0) = 1 because only 1 divides 0! = 1.
a(1) = 1 because only 1 divides 1! = 1.
a(2) = 5 because both 1 and 2 divide 2! = 2, and 1^2 + 2^2 = 5.
a(3) = 50 because 1, 2, 3, 6 divide 3! = 6, and 1^2 + 2^2 + 3^2 + 6^2 = 50.
a(4) = 850 because 1, 2, 3, 4, 6, 8, 12, 24 divide 4! = 24, and 1^2 + 2^2 + 3^2 + 4^2 + 6^2 + 8^2 + 12^2 + 24^2 = 850.
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CROSSREFS
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Cf. A000142, A000203, A001157, A062569.
Sequence in context: A052562 A113132 A088992 this_sequence A051893 A082100 A070995
Adjacent sequences: A116903 A116904 A116905 this_sequence A116907 A116908 A116909
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Mar 15 2006
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