a(n) = 1*3*5 + 3*5*7 + 5*7*9 + ... (n terms).

Terms

a(0) =0a(1) =15a(2) =120a(3) =435a(4) =1128a(5) =2415a(6) =4560a(7) =7875a(8) =12720a(9) =19503a(10) =28680a(11) =40755a(12) =56280a(13) =75855a(14) =100128a(15) =129795a(16) =165600a(17) =208335a(18) =258840a(19) =318003a(20) =386760a(21) =466095a(22) =557040a(23) =660675a(24) =778128a(25) =910575a(26) =1059240a(27) =1225395a(28) =1410360a(29) =1615503