login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Number of permutations of [n] having exactly seven nontrivial cycles.
2

%I #11 Jul 17 2017 02:53:36

%S 135135,11486475,583783200,23434451040,828052325100,27221423409180,

%T 859752405431920,26617555964919920,818486200464162230,

%U 25221598500336187950,783666055857936771520,24658659357394687609600,788174700361283653718300,25647112073453527447490700

%N Number of permutations of [n] having exactly seven nontrivial cycles.

%C A nontrivial cycle has size > 1.

%H Alois P. Heinz, <a href="/A289955/b289955.txt">Table of n, a(n) for n = 14..450</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Permutation">Permutation</a>

%F E.g.f.: (-log(1-x)-x)^7/7!*exp(x).

%t Drop[CoefficientList[Series[(-Log[1 - x] - x)^7/7!*Exp[x] , {x, 0, 50}], x] * Table[k !, {k, 0, 50}] , 14] (* _Indranil Ghosh_, Jul 16 2017 *)

%o (PARI) x = 'x + O('x^30); Vec(serlaplace((-log(1-x)-x)^7/7!*exp(x))) \\ _Michel Marcus_, Jul 16 2017

%Y Column k=7 of A136394.

%K nonn

%O 14,1

%A _Alois P. Heinz_, Jul 16 2017