a(n) = Sum_{k=1..n-1} ceiling(k^2/n).

Terms

a(0) =0a(1) =1a(2) =3a(3) =5a(4) =8a(5) =12a(6) =17a(7) =22a(8) =26a(9) =33a(10) =41a(11) =49a(12) =56a(13) =66a(14) =77a(15) =86a(16) =96a(17) =107a(18) =121a(19) =135a(20) =148a(21) =162a(22) =179a(23) =196a(24) =206a(25) =225a(26) =243a(27) =263a(28) =280a(29) =302