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

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =9a(5) =13a(6) =18a(7) =24a(8) =29a(9) =34a(10) =42a(11) =51a(12) =57a(13) =67a(14) =78a(15) =90a(16) =97a(17) =110a(18) =122a(19) =137a(20) =149a(21) =163a(22) =180a(23) =198a(24) =211a(25) =226a(26) =246a(27) =265a(28) =281a(29) =303