a(n) = ((9+sqrt(3))^n + (9-sqrt(3))^n)/2.

A152056

a(n) = ((9+sqrt(3))^n + (9-sqrt(3))^n)/2.

Terms

    a(0) =1a(1) =9a(2) =84a(3) =810a(4) =8028a(5) =81324a(6) =837648a(7) =8734392a(8) =91882512a(9) =972602640a(10) =10340011584a(11) =110257202592

External references