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A294676
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Ramsey-Comer numbers: a(n) is the smallest prime p congruent to 1 mod 2n such that for every prime q >= p (also congruent to 1 mod 2n), the multiplicative subgroup H of (Z/qZ)* of index n contains a solution to x+y = z.
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1
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3, 13, 19, 73, 131, 313, 547, 193, 613, 1201, 1453, 1249, 547, 2857, 2971, 1601, 4217, 3169, 2243, 4441, 9661, 10957, 7039, 7873, 8951, 11701, 14419, 18257, 11311, 29641
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OFFSET
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1,1
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COMMENTS
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a(n) <= n^4 + 5 (cf. Alm, 2017).
The subgroup H, along with its n-1 cosets, induces a cyclic coloring on K_q. Labeling the vertices 0 through q-1, color the edge uv by the color corresponding to the coset containing u-v (mod q). Thus if q >= a(n), the coloring induced by H and its cosets must contain a monochromatic triangle. In fact, it contains many monochromatic triangles in each color class.
The data gathered thus far suggest that the bound n^4 + 5 can be replaced by cn^3 for some c > 1, but there is no proof.
a(n) > A263308(n). The reason A263308(8) is zero can be taken to be that a(8) is exceptionally small; similarly, a(13) is small, so A263308(13)=0.
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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