A156125 a(n)=10^n*C(2n,n)/C(n+3,3).

1, 5, 60, 1000, 20000, 450000, 11000000, 286000000, 7800000000, 221000000000, 6460000000000, 193800000000000, 5943200000000000, 185725000000000000, 5899500000000000000, 190095000000000000000, 6203100000000000000000

Offset: 0

Author

Paul Barry, Feb 04 2009

Keywords

• easy
• nonn

Comments

Hankel transform is 10^(n^2-1+0^n)*A156126(n).

Programs

Mathematica

Table[10^n Binomial[2n,n]/Binomial[n+3,3],{n,0,20}] (* Harvey P. Dale, Mar 30 2022 *)

Formula

G.f.: F(1/2,1;4;40x);

a(n)=6*10^n*A000108(n)/((n+2)(n+3))=10^(n-1)*A007272(n).

(n+3)*a(n) +20*(1-2*n)*a(n-1)=0. - R. J. Mathar, Oct 25 2012