a(n) = Sum_{k=0..n} binomial(2*k,k)*binomial(2*n-k,k).
A027277
a(n) = Sum_{k=0..n} binomial(2*k,k)*binomial(2*n-k,k).
Terms
- a(0) =1a(1) =3a(2) =13a(3) =67a(4) =375a(5) =2189a(6) =13089a(7) =79479a(8) =487833a(9) =3018355a(10) =18792303a(11) =117589689a(12) =738844719a(13) =4658460165a(14) =29458662005a(15) =186761788579
External references
- oeis: A027277