(2^n+2)*(2^n+4)*(4^n+9*2^n+38)/720.

A030538

(2^n+2)*(2^n+4)*(4^n+9*2^n+38)/720.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =29a(4) =219a(5) =2295a(6) =29359a(7) =418847a(8) =6323967a(9) =98276543a(10) =1549615167a(11) =24613132095a(12) =392371455295

External references