a(n) = 1*2*3*4*5 + 6*7*8*9*10 + 11*12*13*14*15 + ... + (up to n).

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =126a(6) =162a(7) =456a(8) =3144a(9) =30360a(10) =30371a(11) =30492a(12) =32076a(13) =54384a(14) =390720a(15) =390736a(16) =390992a(17) =395616a(18) =483744a(19) =2251200a(20) =2251221a(21) =2251662a(22) =2261826a(23) =2506224a(24) =8626800a(25) =8626826a(26) =8627502a(27) =8646456a(28) =9196824a(29) =25727520