a(n) = ceiling((n + 7/10)^3).

Terms

a(0) =5a(1) =20a(2) =51a(3) =104a(4) =186a(5) =301a(6) =457a(7) =659a(8) =913a(9) =1226a(10) =1602a(11) =2049a(12) =2572a(13) =3177a(14) =3870a(15) =4658a(16) =5546a(17) =6540a(18) =7646a(19) =8870a(20) =10219a(21) =11698a(22) =13313a(23) =15070a(24) =16975a(25) =19035a(26) =21254a(27) =23640a(28) =26199a(29) =28935