A370556 a(n) is the denominator of f(n)*conj(f(n)), where f(n) = Product_{k=1..n} (1/k + i), i is the imaginary unit, and conj(z) is the complex conjugate of z.

1, 2, 9, 144, 72, 2592, 63504, 4064256, 164602368, 658409472, 39833773056, 5736063320064, 2868031660032, 562134205366272, 2529603924148224, 647578604581945344, 323789302290972672, 104907733942275145728, 18935845976580663803904, 302973535625290620862464, 66805664605376581900173312

Offset: 1

Author

Hugo Pfoertner, Feb 23 2024

Keywords

• nonn
• frac
• easy

Crossrefs

A370555 are the corresponding numerators.

Cf. A370547, A370548, A370549, A370550, A370551, A370552, A370553, A370554.

Programs

PARI

a370556(n) = my (f(n)=prod(k=1, n, 1/k + I)); denominator(f(n)*conj(f(n)))