16679706624domain: NAppears in sequencesa(n) is the denominator of the imaginary part of Product_{k=1..n} (1/k + i) where i is the imaginary unit.at n=20A370550a(n) is the denominator of the real part of Product_{k=1..n} (1 + i/k) where i is the imaginary unit.at n=20A370552