OFFSET
1,1
COMMENTS
a(n) = discriminant of extension field defined in A220862.
REFERENCES
David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, Cor. 5.17, p. 105.
FORMULA
Let i = A220862(n). Then a(n) = i if i == 1 (mod 4), otherwise 4i.
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Dec 26 2012
STATUS
approved