a(n) = H(2*n)*(2*n)!/n! where H(n) = Sum_{k=1..n} 1/k, the n-th harmonic number.
A123989
a(n) = H(2*n)*(2*n)!/n! where H(n) = Sum_{k=1..n} 1/k, the n-th harmonic number.
Terms
- a(0) =0a(1) =3a(2) =25a(3) =294a(4) =4566a(5) =88572a(6) =2064504a(7) =56243184a(8) =1754322480a(9) =61664980320
External references
- oeis: A123989