a(n) = (1/n)*Sum_{k=1..n} k*binomial(n,k-1)*binomial(2*n,n-k).
A262394
a(n) = (1/n)*Sum_{k=1..n} k*binomial(n,k-1)*binomial(2*n,n-k).
Terms
- a(0) =1a(1) =4a(2) =20a(3) =110a(4) =637a(5) =3808a(6) =23256a(7) =144210a(8) =904475a(9) =5722860a(10) =36463440a(11) =233646504a(12) =1504152860a(13) =9721421440a(14) =63040282096a(15) =409972529754
External references
- oeis: A262394