a(n) = Sum_{j=1..n} Sum_{i=1..n} (j mod i).

Terms

a(0) =0a(1) =1a(2) =5a(3) =12a(4) =26a(5) =44a(6) =73a(7) =109a(8) =157a(9) =215a(10) =292a(11) =375a(12) =481a(13) =603a(14) =744a(15) =900a(16) =1087a(17) =1287a(18) =1522a(19) =1773a(20) =2053a(21) =2361a(22) =2712a(23) =3073a(24) =3476a(25) =3913a(26) =4389a(27) =4891a(28) =5448a(29) =6021