OFFSET
1,1
COMMENTS
m=1 if p=2, otherwise m=p.
REFERENCES
David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, Cor. 5.17, p. 105.
LINKS
Bruno Berselli, Table of n, a(n) for n = 1..1000
FORMULA
Let p = prime(n). Then a(n) = -4 if p = 2, -p if p == 3 mod 4, -4p if p == 1 mod 4.
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Dec 26 2012
STATUS
approved