a(n) = Sum_{k=0..n} (-1)^k * binomial(5*n-k+1,n-k).
A387756
a(n) = Sum_{k=0..n} (-1)^k * binomial(5*n-k+1,n-k).
Terms
- a(0) =1a(1) =5a(2) =46a(3) =468a(4) =4999a(5) =54922a(6) =614576a(7) =6966380a(8) =79724833a(9) =919145823a(10) =10659130596a(11) =124202877644
External references
- oeis: A387756