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Search: id:A064138
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| A064138 |
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Sum of non-unitary divisors of n!. |
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+0
1
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| 0, 0, 0, 24, 144, 1398, 11184, 97200, 973296, 10950696, 131408352, 1593191808, 22304685312, 333297226080, 5103130001760, 81686161277280, 1470350902991040, 26490792085668288, 529815841713365760, 10635027891469974720
(list; graph; listen)
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OFFSET
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1,4
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,100
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FORMULA
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a(n) = sigma(n!)-usigma(n!) = A000203(n!)-A034448(A000142(n)) = A062569(n)-A034448(n!) = A048105(n!)
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EXAMPLE
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n=6,6!=720, sum of its 30 divisors is 2418, sum of 8 unitary divisors is 1020, so remaining 22 divisors gives a(6)=1398.
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PROGRAM
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(PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) } { n=0; f=1; for (n=1, 100, f*=n; write("b064138.txt", n, " ", sigma(f) - usigma(f)); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 08 2009]
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CROSSREFS
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Cf. A034448, A003444, A048105, A046656, A056657, A056171, A056172, A000203, A000142, A062569, A063955, A063960.
Sequence in context: A001342 A029572 A129923 this_sequence A158047 A042116 A042118
Adjacent sequences: A064135 A064136 A064137 this_sequence A064139 A064140 A064141
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Sep 11 2001
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EXTENSIONS
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Term corrected and more terms added by Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 08 2009
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