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A237610 Positive integers k such that x^2 - 10xy + y^2 + k = 0 has integer solutions. 8
8, 15, 20, 23, 24, 32, 47, 60, 71, 72, 80, 87, 92, 95, 96, 116, 128, 135, 152, 159, 167, 180, 188, 191, 200, 207, 212, 215, 216, 239, 240, 263, 276, 284, 288, 303, 311, 320, 335, 344, 348, 359, 368, 375, 380, 383, 384, 392, 404, 423, 431, 447, 456, 464, 479 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

15 is in the sequence because x^2 - 10xy + y^2 + 15 = 0 has integer solutions, for example (x, y) = (2, 19).

PROG

(PARI) is(n)=m=bnfisintnorm(bnfinit(x^2-10*x+1), -n); #m>0&&denominator(polcoeff(m[1], 1))==1 \\ Ralf Stephan, Feb 11 2014

CROSSREFS

Cf. A072256 (k = 8), A129445 (k = 15), A080806 (k = 20), A074061 (k = 23), A001079 (k = 24).

Cf. A031363, A084917, A237351, A237599, A237606, A237609.

Sequence in context: A247081 A133157 A014544 * A122754 A082867 A075713

Adjacent sequences:  A237607 A237608 A237609 * A237611 A237612 A237613

KEYWORD

nonn

AUTHOR

Colin Barker, Feb 10 2014

STATUS

approved

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Last modified March 26 01:08 EDT 2019. Contains 321479 sequences. (Running on oeis4.)