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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
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1, 1, 1, 6, 33, 75, 877, 2075, 38692, 239794, 1250340, 18495201, 43023264, 4554211553, 70490483945, 911526001064, 182477118528, 219638126087356, 13070186026272, 79249480638985626
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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PROG
| (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
| Sequence in context: A140521 A171141 A069065 * A157872 A153127 A135526
Adjacent sequences: A073340 A073341 A073342 * A073344 A073345 A073346
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KEYWORD
| more,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 23 2002
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EXTENSIONS
| 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
a(14)-a(20) from Robert Gerbicz (robert.gerbicz(AT)gmail.com), Nov 19 2010
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