a(n) = (1/3)*(n+2)^2*(3*n+3)!/(n+2)!^3.
A319578
a(n) = (1/3)*(n+2)^2*(3*n+3)!/(n+2)!^3.
Terms
- a(0) =1a(1) =10a(2) =140a(3) =2310a(4) =42042a(5) =816816a(6) =16628040a(7) =350574510a(8) =7595781050a(9) =168212023980
External references
- oeis: A319578
A319578
a(n) = (1/3)*(n+2)^2*(3*n+3)!/(n+2)!^3.