A370555 a(n) is the numerator 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.

2, 5, 25, 425, 221, 8177, 204425, 13287625, 544792625, 2200962205, 134258694505, 19467510703225, 9791351537125, 1928896252813625, 8718611062717585, 2240683043118419345, 1124218135820660225, 365370894141714573125, 66132131839650337735625, 1060759394707991417279425

Offset: 1

Author

Hugo Pfoertner, Feb 23 2024

Keywords

• nonn
• frac
• easy

Comments

f(n) may also be chosen as Product_{k=1..n} (1 + i/k) without changing the result.

Crossrefs

A370556 are the corresponding denominators.

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

Programs

PARI

a370555(n) = my (f(n)=prod(k=1, n, 1/k+I)); numerator(f(n)*conj(f(n)))