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A264826
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Primitive Eisenstein triples: (a,b,c) in lexicographic order such that a^2 + b^2 - a*b - c^2 = 0, a < b < c, and gcd(a, b) = 1.
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4
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3, 7, 8, 5, 7, 8, 5, 19, 21, 7, 13, 15, 7, 37, 40, 8, 13, 15, 9, 61, 65, 11, 31, 35, 11, 91, 96, 13, 43, 48, 13, 127, 133, 15, 169, 176, 16, 19, 21, 16, 49, 55, 17, 73, 80, 17, 217, 225, 19, 91, 99, 19, 271, 280, 21, 331, 341, 23, 133, 143, 23, 397, 408
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OFFSET
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1,1
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COMMENTS
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The sides of a primitive 60-degree integer triangle.
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LINKS
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PROG
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(PARI)
pt60(a) = {
my(L=List(), n=-3*a^2, f, g, b, c);
fordiv(n, f,
g=n\f;
if(f>g && (g+f)%2==0 && (f-g)%4==0,
b=(f-g)\4; c=((f+g)\2+a)\2;
if(c>0 && a<b && gcd(a, c)==1, listput(L, [a, b, c]))
)
);
Vec(L)
}
concat(concat(vector(30, a, pt60(a))))
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CROSSREFS
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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