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A238240
Positive integers n such that x^2 - 20xy + y^2 + n = 0 has integer solutions.
3
18, 35, 50, 63, 72, 74, 83, 90, 95, 98, 99, 107, 140, 162, 171, 200, 215, 227, 252, 266, 275, 288, 296, 315, 332, 347, 359, 360, 362, 371, 380, 387, 392, 395, 396, 407, 428, 450, 491, 495, 530, 539, 560, 567, 602, 623, 626, 635, 648, 666, 684, 695, 711, 722, 743, 747, 755, 770, 791, 794, 800, 810
OFFSET
1,1
COMMENTS
Positive integers n such that x^2 - 99 y^2 + n = 0 has integer solutions. - Robert Israel, Oct 22 2024
LINKS
EXAMPLE
63 is in the sequence because x^2 - 20xy + y^2 + 63 = 0 has integer solutions, for example (x, y) = (1, 16).
MAPLE
filter:= t -> [isolve(99*y^2 - z^2 = t)] <> []:
select(filter, [$1..1000]); # Robert Israel, Oct 22 2024
CROSSREFS
Cf. A075839 (n = 18), A221763 (n = 63), A198947 (n = 90), A001085 (n = 99).
Sequence in context: A044444 A250770 A014640 * A245587 A215137 A160844
KEYWORD
nonn
AUTHOR
Colin Barker, Feb 20 2014
EXTENSIONS
Corrected by Robert Israel, Oct 22 2024
STATUS
approved