a(n) = Sum_{k=0..n} (k+2) * binomial(4*n-3*k+2,n-k)/(4*n-3*k+2).
A390720
a(n) = Sum_{k=0..n} (k+2) * binomial(4*n-3*k+2,n-k)/(4*n-3*k+2).
Terms
- a(0) =1a(1) =3a(2) =13a(3) =72a(4) =459a(5) =3183a(6) =23315a(7) =177449a(8) =1389355a(9) =11117962a(10) =90523311a(11) =747511830a(12) =6245348236a(13) =52696347125a(14) =448402255002
External references
- oeis: A390720