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A237704 Numbers n for which the fundamental solution of Pell's equation x^2 - n*y^2 = 1 has both x and y prime. 1
2, 6, 12, 30, 32, 40, 42, 72, 90, 132, 152, 192, 210, 240, 312, 342, 408, 420, 462, 480, 552, 560, 592, 672, 702, 792, 870, 880, 888, 912, 930, 1122, 1152, 1260, 1272, 1320, 1332, 1560, 1584, 1722, 1752, 1792, 1980, 2352, 2520, 2550, 2652, 2712, 2862, 2952, 2970, 3192, 3560, 3640, 4032 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ray Chandler, Table of n, a(n) for n = 1..716

Wikipedia, Pell's equation

EXAMPLE

Pell's equation x^2 - 2*y^2 = 1 and its fundamental solution is (x,y) = (3,2) which are both primes, so a(1) = 2.

(x,y) = (5,2) satisfies x^2 - 6*y^2 = 1, so a(2) = 6.

(x,y) = (7,2) satisfies x^2 - 12*y^2 = 1, so a(3) = 12.

Pell's equation x^2 - 2088*y^2 = 1 and (x,y) = (19603, 429), 19603 is prime, 429 = 3 * 11 * 13 is not, so 2088 is not included.

Pell's equation x^2 - 2000*y^2 = 1 and (x,y) = (930249, 20801), 930249 = 3^2 * 41 * 2521 and 20801 = 11 * 31 * 61 are not primes, so 2000 is not included.

CROSSREFS

Cf. A000037, A033313, A033317.

Sequence in context: A195166 A225646 A225627 * A181826 A143176 A081375

Adjacent sequences:  A237701 A237702 A237703 * A237705 A237706 A237707

KEYWORD

nonn

AUTHOR

Jani Melik, Feb 11 2014

EXTENSIONS

420 inserted into the sequence by Colin Barker, Feb 12 2014

STATUS

approved

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Last modified July 23 01:27 EDT 2019. Contains 325228 sequences. (Running on oeis4.)