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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
OFFSET
1,1
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).
Sequence in context: A247081 A133157 A014544 * A122754 A355490 A082867
KEYWORD
nonn
AUTHOR
Colin Barker, Feb 10 2014
STATUS
approved