a(n) = round(n*phi^6), where phi is the golden ratio, A001622.

Terms

a(0) =0a(1) =18a(2) =36a(3) =54a(4) =72a(5) =90a(6) =108a(7) =126a(8) =144a(9) =161a(10) =179a(11) =197a(12) =215a(13) =233a(14) =251a(15) =269a(16) =287a(17) =305a(18) =323a(19) =341a(20) =359a(21) =377a(22) =395a(23) =413a(24) =431a(25) =449a(26) =467a(27) =484a(28) =502a(29) =520