a(n) = (1/n)*Sum_{k=0..n} binomial(n, k)*binomial(n+k, k+1)*binomial(n+k, k) with a(0) = 1.
A073530
a(n) = (1/n)*Sum_{k=0..n} binomial(n, k)*binomial(n+k, k+1)*binomial(n+k, k) with a(0) = 1.
Terms
- a(0) =1a(1) =3a(2) =22a(3) =225a(4) =2706a(5) =35861a(6) =507060a(7) =7510005a(8) =115175530a(9) =1815002145a(10) =29231242206a(11) =479251119815
External references
- oeis: A073530