a(n) = Sum_{2*i+3*j=n, 0<=i<=n, 0<=j<=n} n!/( (2*i)!*(3*j)! ).

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =1a(5) =10a(6) =2a(7) =35a(8) =29a(9) =85a(10) =211a(11) =220a(12) =926a(13) =1001a(14) =3095a(15) =5461a(16) =9829a(17) =25126a(18) =37130a(19) =97223a(20) =164921a(21) =349525a(22) =728575a(23) =1309528a(24) =2973350a(25) =5326685a(26) =11450531a(27) =22369621a(28) =43942081a(29) =91869970