A092469 a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (n+2j)!/(i! * (3j)! * k!).

1, 1, 13, 91, 1081, 10606, 181189, 2025325, 38378449, 548523856, 10811257051, 176339404099, 3828413138785, 68734868302738, 1590128353317001, 31543123841374681, 768191679788034529, 16494997547298477340

Offset: 0

Author

Benoit Cloitre, Mar 25 2004

Keywords

• nonn

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..500 (terms 0..200 from Seiichi Manyama)

Crossrefs

Cf. A092468.

Programs

PARI

a(n)=sum(i=0,n,sum(j=0,i,sum(k=0,j,if(i+j+k-n,0,(n+2*j)!/i!/(2*j)!/k!))))