A073343 Number of permutations p of (1,2,3,...,n) such that Sum_{k=1..n} gcd(k,p(k)) = sigma(n).

1, 1, 1, 6, 33, 75, 877, 2075, 38692, 239794, 1250340, 18495201, 43023264, 4554211553, 70490483945, 911526001064, 182477118528, 219638126087356, 13070186026272, 79249480638985626

Offset

1,4

Links

Table of n, a(n) for n=1..20.

Prog

(PARI) a(n)=sum(k=1, n!, if(sum(i=1, n, gcd(i, component(numtoperm(n, k), i)))-sigma(n), 0, 1))

Crossrefs

Sequence in context: A140521 A171141 A069065 * A157872 A153127 A274218

Adjacent sequences: A073340 A073341 A073342 * A073344 A073345 A073346

Keyword

more,nonn

Author

Benoit Cloitre, Aug 23 2002

Extensions

a(10) from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 14 2004

a(11) from Rick L. Shepherd, Mar 15 2004

a(12)-a(13) from Ryan Propper, Oct 25 2006

a(14)-a(20) from Robert Gerbicz, Nov 19 2010

Status

approved