OFFSET
1,2
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..526
Elżbieta Liszewska, Wojciech Młotkowski, Some relatives of the Catalan sequence, arXiv:1907.10725 [math.CO], 2019.
FORMULA
a(n) = 9^(n-1)*A045756(n)/n!, A045756(n)=(9*n-8)(!^9) := product(9*j-8, j=1..n); G.f. (-1+(1-81*x)^(-1/9))/9.
D-finite with recurrence: n*a(n) +9*(-9*n+8)*a(n-1)=0. - R. J. Mathar, Jan 28 2020
MATHEMATICA
CoefficientList[Series[(1/(1-81 x)^(1/9)-1)/(9 x), {x, 0, 20}], x] (* Harvey P. Dale, May 14 2011 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
STATUS
approved