a(n) = Sum_{k=0..n} (-1)^k * binomial(4*n+k,n-k).
A390571
a(n) = Sum_{k=0..n} (-1)^k * binomial(4*n+k,n-k).
Terms
- a(0) =1a(1) =3a(2) =20a(3) =155a(4) =1275a(5) =10829a(6) =93841a(7) =824526a(8) =7318324a(9) =65460251a(10) =589108377a(11) =5327945572a(12) =48383667123a(13) =440888776266
External references
- oeis: A390571