a(n) = 10^n*C(2n,n)/C(n+3,3).
A156125
a(n) = 10^n*C(2n,n)/C(n+3,3).
Terms
- a(0) =1a(1) =5a(2) =60a(3) =1000a(4) =20000a(5) =450000a(6) =11000000a(7) =286000000a(8) =7800000000a(9) =221000000000
External references
- oeis: A156125
A156125
a(n) = 10^n*C(2n,n)/C(n+3,3).