a(n) = Sum_{k=0..n} (1-i)^k * (1+i)^(n-k) * binomial(n+3,k) * binomial(n+3,n-k), where i is the imaginary unit.
A387403
a(n) = Sum_{k=0..n} (1-i)^k * (1+i)^(n-k) * binomial(n+3,k) * binomial(n+3,n-k), where i is the imaginary unit.
Terms
- a(0) =1a(1) =8a(2) =50a(3) =280a(4) =1484a(5) =7616a(6) =38304a(7) =190080a(8) =934560a(9) =4564736a(10) =22189024a(11) =107476096a(12) =519180480a(13) =2502850560a(14) =12046666752a(15) =57912029184a(16) =278136798720
External references
- oeis: A387403