A237609 Positive integers k such that x^2 - 9xy + y^2 + k = 0 has integer solutions.

7, 13, 17, 19, 28, 41, 52, 61, 63, 68, 73, 76, 77, 83, 101, 112, 117, 131, 139, 143, 153, 161, 164, 167, 171, 173, 175, 187, 208, 209, 227, 241, 244, 252, 259, 271, 272, 283, 292, 293, 299, 304, 307, 308, 325, 332, 343, 349, 369, 371, 391, 404, 409, 425, 437

Offset

1,1

Links

Table of n, a(n) for n=1..55.

Example

7 is in the sequence because x^2 - 9xy + y^2 + 7 = 0 has integer solutions, for example (x, y) = (1, 8).

Prog

(PARI) is(n)=bnfisintnorm(bnfinit(x^2-9*x+1), -n) \\ Ralf Stephan, Feb 11 2014

Crossrefs

Cf. A070998 (k = 7).

Cf. A031363, A084917, A237351, A237599, A237606, A237610.

Sequence in context: A079697 A079695 A079698 * A038906 A097959 A156543

Adjacent sequences: A237606 A237607 A237608 * A237610 A237611 A237612

Keyword

nonn

Author

Colin Barker, Feb 10 2014

Status

approved