OFFSET
1,1
EXAMPLE
15 is in the sequence because x^2 - 10xy + y^2 + 15 = 0 has integer solutions, for example (x, y) = (2, 19).
PROG
(PARI) is(n)=m=bnfisintnorm(bnfinit(x^2-10*x+1), -n); #m>0&&denominator(polcoeff(m[1], 1))==1 \\ Ralf Stephan, Feb 11 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Colin Barker, Feb 10 2014
STATUS
approved