a(n) = 1*2 + 3 + 4*5 + 6 + 7*8 + 9 + 10*11 + 12 + ... + (up to n).

Terms

a(0) =1a(1) =2a(2) =5a(3) =9a(4) =25a(5) =31a(6) =38a(7) =87a(8) =96a(9) =106a(10) =206a(11) =218a(12) =231a(13) =400a(14) =415a(15) =431a(16) =687a(17) =705a(18) =724a(19) =1085a(20) =1106a(21) =1128a(22) =1612a(23) =1636a(24) =1661a(25) =2286a(26) =2313a(27) =2341a(28) =3125a(29) =3155