-6610domain: ZAppears in sequencesG.f.: (1 - x/(1 - x^2/(1 - x^3/(1 - x^4/(1 - ...))))) / (1 + x/(1 + x^2/(1 + x^3/(1 + x^4/(1 + ...))))), a continued fraction.at n=33A285635a(n) = 1*2*3 - 4*5*6 + 7*8*9 - 10*11*12 + 13*14*15 - ... + (up to n).at n=25A319543