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A243655
Positive numbers that are primitively represented by the indefinite quadratic form x^2 - 3y^2 of discriminant 12.
13
1, 6, 13, 22, 33, 37, 46, 61, 69, 73, 78, 94, 97, 109, 118, 121, 141, 142, 157, 166, 169, 177, 181, 193, 213, 214, 222, 229, 241, 249, 253, 262, 277, 286, 313, 321, 334, 337, 349, 358, 366, 373, 382, 393, 397, 409, 421, 429, 433, 438, 454, 457, 478, 481
OFFSET
1,2
COMMENTS
x^2+2xy-2y^2 is an equivalent form.
MATHEMATICA
Reap[For[n = 1, n < 500, n++, r = Reduce[x^2 - 3 y^2 == n, {x, y}, Integers]; If[r =!= False, If[AnyTrue[{x, y} /. {ToRules[r /. C[1] -> 0]}, CoprimeQ @@ # &], Print[n]; Sow[n]]]]][[2, 1]] (* Jean-François Alcover, Oct 31 2016 *)
CROSSREFS
Cf. A084916 (all numbers represented), A068228.
Sequence in context: A056115 A173358 A101247 * A072212 A028872 A049718
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 11 2014
STATUS
approved

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Last modified September 20 15:43 EDT 2024. Contains 376073 sequences. (Running on oeis4.)