a(n) = Sum_{d|10} phi(d)*n^(10/d).

Terms

a(0) =0a(1) =10a(2) =1080a(3) =59340a(4) =1049680a(5) =9768870a(6) =60474120a(7) =282492280a(8) =1073774880a(9) =3486843810a(10) =10000100440a(11) =25937586180a(12) =61917613680a(13) =137858863870a(14) =289255193640a(15) =576651150960