a(n) = (4*0^n + 5^n*binomial(2*n,n))/5.
A099046
a(n) = (4*0^n + 5^n*binomial(2*n,n))/5.
Terms
- a(0) =1a(1) =2a(2) =30a(3) =500a(4) =8750a(5) =157500a(6) =2887500a(7) =53625000a(8) =1005468750a(9) =18992187500a(10) =360851562500
External references
- oeis: A099046