A091731 - OEIS

%I #11 Mar 21 2023 09:18:16

%S 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,

%T 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

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

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

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

%F See A091730.

%K nonn,more

%O 0,7

%A _Paul Boddington_, Feb 02 2004