a(n) = Sum_{k=0..n} binomial(4*n+k,n).
A391542
a(n) = Sum_{k=0..n} binomial(4*n+k,n).
Terms
- a(0) =1a(1) =9a(2) =109a(3) =1325a(4) =15981a(5) =191470a(6) =2283471a(7) =27152235a(8) =322294765a(9) =3822163565a(10) =45314215530a(11) =537292624687
External references
- oeis: A391542