a(n) = (9*n + 6)^5.

Terms

a(0) =7776a(1) =759375a(2) =7962624a(3) =39135393a(4) =130691232a(5) =345025251a(6) =777600000a(7) =1564031349a(8) =2887174368a(9) =4984209207a(10) =8153726976a(11) =12762815625a(12) =19254145824a(13) =28153056843a(14) =40074642432a(15) =55730836701a(16) =75937500000a(17) =101621504799a(18) =133827821568a(19) =173726604657a(20) =222620278176a(21) =281950621875a(22) =353305857024