a(n) = Sum_{k=0..n} C(n,k)^2*C(n+k,k)^3, where C := binomial.
A111968
a(n) = Sum_{k=0..n} C(n,k)^2*C(n+k,k)^3, where C := binomial.
Terms
- a(0) =1a(1) =9a(2) =325a(3) =17577a(4) =1152501a(5) =84505509a(6) =6664647781a(7) =553268669865
External references
- oeis: A111968