OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: x * (1 +92368*x +18396110*x^2 +371157402*x^3 +1763669368*x^4 +2567824154*x^5 +1206169122*x^6 +163325950*x^7 +4293143*x^8 +4862*x^9) / (x-1)^10.
a(0) = 0, a(n) = 1 +(18 +(152 +(798 +(2907 +(7752 +(15504 +(23256 +(25194 +16796*(n-1)) *(n-1)) *(n-1)) *(n-1)) *(n-1)) *(n-1)) *(n-1)) * (n-1)) * (n-1) for n>0.
EXAMPLE
a(1) = 1: a^20 (with 1-ary alphabet {a}).
MAPLE
a:= n-> `if`(n=0, 0, (x-> 1+(18+(152+(798+(2907+(7752+(15504+(23256+
(25194+16796*x)*x)*x)*x)*x)*x)*x)*x)*x)(n-1)):
seq(a(n), n=0..30);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Sep 02 2011
STATUS
approved