a(n) = floor((n + 1/2)^4).

Terms

a(0) =0a(1) =5a(2) =39a(3) =150a(4) =410a(5) =915a(6) =1785a(7) =3164a(8) =5220a(9) =8145a(10) =12155a(11) =17490a(12) =24414a(13) =33215a(14) =44205a(15) =57720a(16) =74120a(17) =93789a(18) =117135a(19) =144590a(20) =176610a(21) =213675a(22) =256289a(23) =304980a(24) =360300a(25) =422825a(26) =493155a(27) =571914a(28) =659750a(29) =757335