a(n) = 5 + 4^n + 3*((-i*sqrt(7) - 3)^n + (i*sqrt(7) - 3)^n)/2^n.

A370846

a(n) = 5 + 4^n + 3*((-i*sqrt(7) - 3)^n + (i*sqrt(7) - 3)^n)/2^n.

Terms

    a(0) =0a(1) =24a(2) =96a(3) =168a(4) =1200a(5) =3960a(6) =16128a(7) =66888a(8) =259152a(9) =1052184a(10) =4195488a(11) =16759272a(12) =67158000a(13) =268359864a(14) =1073772096a(15) =4295178888a(16) =17179113360a(17) =68720897880a(18) =274876666848

External references