OFFSET
1,3
COMMENTS
Discriminant 77.
In general, for k>=0 the positive part of the set S = {x^2 - k*x*y + y^2: x,y in Z} is given by the numbers of the form x^2 + k*x*y + y^2 with 0 <= x <= y natural numbers.
LINKS
Gheorghe Coserea, Table of n, a(n) for n = 1..100001
PROG
(PARI)
seq(M, k=9) = { \\ assume k >= 0
setintersect([1..M], setbinop((x, y)->x^2 + k*x*y + y^2, [0..1+sqrtint(M)]));
};
concat(0, seq(449))
CROSSREFS
KEYWORD
nonn
AUTHOR
Gheorghe Coserea, Jul 29 2018
STATUS
approved