a(n) = Sum_{k=0..n} (4*n)! / (k! * (n-k)!)^4.

A345646

a(n) = Sum_{k=0..n} (4*n)! / (k! * (n-k)!)^4.

Terms

    a(0) =1a(1) =48a(2) =45360a(3) =60614400a(4) =114144030000

External references