a(n) = Catalan(n)*(3^(n+1) - 2^(n+1) + 1)/2.

A063017

a(n) = Catalan(n)*(3^(n+1) - 2^(n+1) + 1)/2.

Terms

    a(0) =1a(1) =3a(2) =20a(3) =165a(4) =1484a(5) =13986a(6) =135960a(7) =1352637a(8) =13707980a(9) =141061206a(10) =1470489800a(11) =15500280978a(12) =164967244792

External references