a(n) = floor((n + 1/2)^3).

Terms

a(0) =0a(1) =3a(2) =15a(3) =42a(4) =91a(5) =166a(6) =274a(7) =421a(8) =614a(9) =857a(10) =1157a(11) =1520a(12) =1953a(13) =2460a(14) =3048a(15) =3723a(16) =4492a(17) =5359a(18) =6331a(19) =7414a(20) =8615a(21) =9938a(22) =11390a(23) =12977a(24) =14706a(25) =16581a(26) =18609a(27) =20796a(28) =23149a(29) =25672