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Search: id:A073343
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| A073343 |
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Number of permutations p of (1,2,3,...,n) such that sum(k=1,n,gcd(k,p(k)) = sigma(n). |
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+0
1
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| 1, 1, 1, 6, 33, 75, 877, 2075, 38692, 239794, 1250340, 18495201, 43023264
(list; graph; listen)
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OFFSET
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1,4
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PROGRAM
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(PARI) a(n)=sum(k=1, n!, if(sum(i=1, n, gcd(i, component(numtoperm(n, k), i)))-sigma(n), 0, 1))
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CROSSREFS
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Sequence in context: A132548 A140521 A069065 this_sequence A157872 A153127 A135526
Adjacent sequences: A073340 A073341 A073342 this_sequence A073344 A073345 A073346
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KEYWORD
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more,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 23 2002
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EXTENSIONS
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a(10) from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 14 2004
a(11) from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Mar 15 2004
2 more terms from Ryan Propper (rpropper(AT)stanford.edu), Oct 25 2006
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