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

Author

Paul Boddington, Feb 02 2004

Keywords

• nonn
• more

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.

Formula

See A091730.