A091731 Number of irreducible elements of Z[sqrt(-5)] of norm n (counting a and -a once only).

0, 0, 0, 0, 1, 1, 2, 0, 0, 3, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2

Offset

0,7

References

David A. Cox, Primes of the form x^2+ny^2, Wiley, 1989.

A. Frohlich and M. J. Taylor, Algebraic number theory, Cambridge university press, 1991.

Links

Table of n, a(n) for n=0..61.

Formula

See A091730.

Crossrefs

Sequence in context: A169776 A240766 A265494 * A284269 A140579 A132681

Adjacent sequences: A091728 A091729 A091730 * A091732 A091733 A091734

Keyword

nonn,more

Author

Paul Boddington, Feb 02 2004

Status

approved