a(n) = binomial(4n,2n) or (4*n)!/((2*n)!*(2*n)!).
A001448
a(n) = binomial(4n,2n) or (4*n)!/((2*n)!*(2*n)!).
Terms
- a(0) =1a(1) =6a(2) =70a(3) =924a(4) =12870a(5) =184756a(6) =2704156a(7) =40116600a(8) =601080390a(9) =9075135300a(10) =137846528820
External references
- oeis: A001448