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Search: id:A064852
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| 1, 0, 0, 1, 4, 18, 102, 624, 4476, 36248, 329890, 3326054, 36846276, 444783906, 5811885808, 81729607680, 1230752346352, 19760412095328, 336967037143578, 6082255011151724, 115852476579789984, 2322315553090615850
(list; graph; listen)
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OFFSET
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1,5
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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) = Sum_{k|n} mu(n/k)*phi(n/k)*(n/k)^k*k!/n^2 = A047918(n, n)/n^2.
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EXAMPLE
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n=6: The orbit {(124635)(235146)(346251)(451362)(562413)(613524)} consists of 6 single permutations
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PROGRAM
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(PARI) for(n=1, 23, print(sumdiv(n, d, moebius(n/d)*eulerphi(n/d)*(n/d)^d*d!/n^2)))
(PARI) { for (n=1, 100, a=sumdiv(n, d, moebius(n/d)*eulerphi(n/d)*(n/d)^d*d!/n^2); write("b064852.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 28 2009]
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CROSSREFS
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Cf. A002619.
Sequence in context: A084832 A135177 A137958 this_sequence A159666 A051827 A007711
Adjacent sequences: A064849 A064850 A064851 this_sequence A064853 A064854 A064855
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KEYWORD
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nice,nonn
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AUTHOR
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Michael Steyer (m.steyer(AT)osram.de), Oct 06 2001
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EXTENSIONS
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Corrected and extended by Jason Earls (zevi_35711(AT)yahoo.com) and Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 08 2001
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