-5398802640domain: ZAppears in sequencesa(n) = 1*2*3*4*5*6*7 - 8*9*10*11*12*13*14 + 15*16*17*18*19*20*21 - ... + (up to n).at n=27A319547a(n) = 7*6*5*4*3*2*1 - 14*13*12*11*10*9*8 + 21*20*19*18*17*16*15 - ... + (up to the n-th term).at n=27A319890