a(n) = Sum_{k=1..n} lcm(n,k).

Terms

a(0) =1a(1) =4a(2) =12a(3) =24a(4) =55a(5) =66a(6) =154a(7) =176a(8) =279a(9) =320a(10) =616a(11) =468a(12) =1027a(13) =910a(14) =1110a(15) =1376a(16) =2329a(17) =1656a(18) =3268a(19) =2320a(20) =3171a(21) =3674a(22) =5842a(23) =3624a(24) =6525a(25) =6136a(26) =7398a(27) =6636a(28) =11803a(29) =6630