a(n) = 4^n*(4^n+1)/2.

A026244

a(n) = 4^n*(4^n+1)/2.

Terms

    a(0) =1a(1) =10a(2) =136a(3) =2080a(4) =32896a(5) =524800a(6) =8390656a(7) =134225920a(8) =2147516416a(9) =34359869440a(10) =549756338176

External references