a(n) = (10 / ((3*n+1)*(3*n+2))) * binomial(4*n, n).

A197271

a(n) = (10 / ((3*n+1)*(3*n+2))) * binomial(4*n, n).

Terms

    a(0) =5a(1) =2a(2) =5a(3) =20a(4) =100a(5) =570a(6) =3542a(7) =23400a(8) =161820a(9) =1159400a(10) =8544965a(11) =64448228a(12) =495508780a(13) =3872033900a(14) =30680401500a(15) =246041115600

External references