A128574 Row 4 of table A128570.
1, 5, 60, 1020, 21420, 523320, 14399280, 437433780, 14479664640, 517426156800, 19824547680000, 810083131361280, 35155640625638400, 1614680474921256960, 78256021787814850560, 3991780109967777792000, 213813097136418588641280
Offset: 0
Keywords
Links
- Vaclav Kotesovec, Table of n, a(n) for n = 0..360
Crossrefs
Programs
-
PARI
{a(n)=local(A=1+(n+5)*x);for(j=0,n,A=1+(n+5-j)*x*A^2 +x*O(x^n)); polcoeff(A,n)}
Formula
G.f.: A(x) = 1 + 5x*R(x,5)^2, where R(x,5) = 1 + 6*x*R(x,6)^2, R(x,6) = 1 + 7*x*R(x,7)^2, ..., R(x,n) = 1 + (n+1)*x*R(x,n+1)^2, ... and R(x,n) is the g.f. of row n of table A128570.
a(n) ~ 32*n^4*A128318(n)/243. - Vaclav Kotesovec, Mar 19 2016