a(n) = Sum_{k=0..n} C((n-k)*k, k) * C((n-k)*k, n-k).
A137645
a(n) = Sum_{k=0..n} C((n-k)*k, k) * C((n-k)*k, n-k).
Terms
- a(0) =1a(1) =0a(2) =1a(3) =4a(4) =42a(5) =608a(6) =10986a(7) =240492a(8) =6167112a(9) =181154848a(10) =5995624710a(11) =220711502648
External references
- oeis: A137645