-617315066615domain: ZAppears in sequencesa(n) is the numerator of the imaginary part of Product_{k=1..n} (1/k + i) where i is the imaginary unit.at n=21A370549a(n) is the numerator of the imaginary part of Product_{k=1..n} (1 + i/k) where i is the imaginary unit.at n=21A370553