1-1, 2*3-(2+3), 4*5*6-(4+5+6), 7*8*9*10-(7+8+9+10), ...

A075350

1-1, 2*3-(2+3), 4*5*6-(4+5+6), 7*8*9*10-(7+8+9+10), ...

Terms

    a(0) =0a(1) =1a(2) =105a(3) =5006a(4) =360295a(5) =39069969a(6) =5967561425

External references