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

1,1

Comments

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

Links

Table of n, a(n) for n=1..20.

Prog

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

Crossrefs

A370556 are the corresponding denominators.

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

Sequence in context: A015486 A191951 A356674 * A120767 A051771 A008318

Adjacent sequences: A370552 A370553 A370554 * A370556 A370557 A370558

Keyword

nonn,frac,easy

Author

Hugo Pfoertner, Feb 23 2024

Status

approved