This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A052860 #26 Jul 14 2024 15:30:42
%S A052860 0,1,2,9,56,440,4164,46046,582336,8288136,131090880,2280970032,
%T A052860 43298796672,890441326320,19720847692896,467964024901200,
%U A052860 11844861486802944,318549937907204352,9070876711252816128,272648086802525651328,8626452694650322744320
%N A052860 A simple grammar: rooted sequences of cycles.
%C A052860 Note that here the root is not allowed to be part of the sequence of cycles. We select a root and then form sequences from the cycles in the permutations of the remaining n-1 elements. Cf. A218817. - _Geoffrey Critzer_, Nov 06 2012
%H A052860 Alois P. Heinz, <a href="/A052860/b052860.txt">Table of n, a(n) for n = 0..150</a>
%H A052860 INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=828">Encyclopedia of Combinatorial Structures 828</a>
%F A052860 E.g.f.: -1/(-1+log(-1/(-1+x)))*x.
%F A052860 a(n) = n*A007840(n-1). a(n) = n!*Sum_{k=0..n-1} a(k)/k!/(n-k) for n>=1 with a(0)=0. - _Paul D. Hanna_, Jul 19 2006
%F A052860 a(n) ~ n! * exp(n-1) / (exp(1)-1)^n. - _Vaclav Kotesovec_, Mar 16 2014
%p A052860 spec := [S,{C=Cycle(Z),B=Sequence(C),S=Prod(Z,B)},labeled]: seq(combstruct[count](spec,size=n), n=0..20);
%t A052860 nn=20;a=Log[1/(1-x)];Range[0,nn]!CoefficientList[Series[x/(1-a) ,{x,0,nn}],x] (* _Geoffrey Critzer_, Nov 06 2012 *)
%o A052860 (PARI) a(n)=n!*polcoeff(x/(1+log(1-x +x*O(x^n))),n) \\ _Paul D. Hanna_, Jul 19 2006
%Y A052860 Cf. A007840.
%K A052860 easy,nonn
%O A052860 0,3
%A A052860 encyclopedia(AT)pommard.inria.fr, Jan 25 2000