a(n) = Sum_{k=1..n} (lcm(n,n-1,...,n-k+2,n-k+1)/lcm(1,2,...,k)).

Terms

a(0) =1a(1) =3a(2) =7a(3) =13a(4) =31a(5) =38a(6) =113a(7) =165a(8) =265a(9) =420a(10) =1607a(11) =1004a(12) =3979a(13) =6893a(14) =4205a(15) =8665a(16) =40903a(17) =49558a(18) =315477a(19) =162320a(20) =79179a(21) =269877a(22) =1647123a(23) =937552a(24) =1810091a(25) =8445653a(26) =7791355a(27) =3978237a(28) =33071543a(29) =19578860