a(n) = 4^(n-2)*n*(5*n+3)/2.

Terms

a(0) =0a(1) =1a(2) =13a(3) =108a(4) =736a(5) =4480a(6) =25344a(7) =136192a(8) =704512a(9) =3538944a(10) =17367040a(11) =83623936a(12) =396361728a(13) =1853882368a(14) =8573157376a(15) =39258685440a(16) =178241142784a(17) =803158884352