a(n) = Sum_{k + l*m <= n} (k + l*m), with 0 <= k,l,m <= n.

Terms

a(0) =0a(1) =4a(2) =22a(3) =64a(4) =144a(5) =269a(6) =461a(7) =720a(8) =1072a(9) =1522a(10) =2092a(11) =2774a(12) =3626a(13) =4614a(14) =5776a(15) =7126a(16) =8694a(17) =10445a(18) =12461a(19) =14684a(20) =17204a(21) =19997a(22) =23077a(23) =26412a(24) =30156a(25) =34206a(26) =38600a(27) =43352a(28) =48532a(29) =54042