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

Terms

a(0) =1a(1) =5a(2) =36a(3) =286a(4) =2380a(5) =20349a(6) =177100a(7) =1560780a(8) =13884156a(9) =124403620a(10) =1121099408a(11) =10150595910a(12) =92263734836a(13) =841392966470