A227939 Values of n such that the equation x^2 - 2*n*y^2 = n has integer solutions.

1, 3, 4, 9, 11, 12, 16, 19, 25, 27, 33, 36, 43, 44, 48, 49, 51, 57, 59, 64, 67, 73, 75, 76, 81, 83, 89, 99, 100, 107, 108, 121, 123, 129, 131, 132, 139, 144, 147, 163, 169, 171, 172, 176, 177, 179, 187, 192

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..440

Example

59 appears in the sequence because the equation x^2 - 118*y^2 = 59 has integer solutions.

Mathematica

Select[Range[200], Length[FullSimplify[Solve[x^2-2*#*y^2==#, {x, y}, Integers]/.C[1]->1]]>0&] (* Vaclav Kotesovec, Oct 08 2013 *)

Crossrefs

Cf. A172000, A229848

Sequence in context: A172980 A336930 A035252 * A047459 A177943 A091380

Adjacent sequences: A227936 A227937 A227938 * A227940 A227941 A227942

Keyword

nonn

Author

Colin Barker, Oct 07 2013

Status

approved