a(n) = floor(6^n/n).

Terms

a(0) =6a(1) =18a(2) =72a(3) =324a(4) =1555a(5) =7776a(6) =39990a(7) =209952a(8) =1119744a(9) =6046617a(10) =32981550a(11) =181398528a(12) =1004668770a(13) =5597440292a(14) =31345665638a(15) =176319369216a(16) =995685849690