a(n) = Sum_{k=0..[n/2]} binomial((n-k)^2, n*k-k^2).
A209331
a(n) = Sum_{k=0..[n/2]} binomial((n-k)^2, n*k-k^2).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =7a(4) =86a(5) =1905a(6) =66002a(7) =5218373a(8) =1340847046a(9) =688750226335
External references
- oeis: A209331