|
|
A356488
|
|
Numbers k such that the equation x^2 - k*y^4 = -1 has a solution for which |y| > 2.
|
|
0
|
|
|
2, 53, 314, 1042, 1685, 1825, 3281, 4586, 5521, 6770, 8597, 9050, 11509, 13858, 17498, 20369, 24737, 28085, 28130, 29041, 31226, 33226, 37141, 37585, 42965, 47402, 49205, 53954, 57125, 58913, 66193, 71674, 79682, 85685, 94421, 100946, 110410, 113290, 115202
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
For k > 2, the equation x^2 - k*y^4 = -1 has at most one positive integer solution. If this solution (x, y) exists, we have v = y^2, where v is the smallest integer satisfying the Pell equation u^2 - k*v^2 = -1 (A130227).
|
|
LINKS
|
|
|
EXAMPLE
|
The equation x^2 - 2*y^4 = -1 has only two positive solutions (1, 1) and (239, 13), so 2 is in the sequence.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|