-518878080domain: 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*22*23*24 - ... + (up to n).at n=15A319549a(n) = 8*7*6*5*4*3*2*1 - 16*15*14*13*12*11*10*9 + 24*23*22*21*20*19*18*17 - ... + (up to the n-th term).at n=15A319891