a(n) = 0 + 1*2 + 3*4*5 + 6*7*8*9 + ... + ...*n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =14a(5) =62a(6) =68a(7) =104a(8) =398a(9) =3086a(10) =3096a(11) =3196a(12) =4406a(13) =20246a(14) =243326a(15) =243341a(16) =243566a(17) =247406a(18) =316766a(19) =1638686a(20) =28150526a(21) =28150547a(22) =28150988a(23) =28161152a(24) =28405550a(25) =34526126a(26) =193916126a(27) =4503821726a(28) =4503821754a(29) =4503822538