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A049245 Smallest nonnegative value taken on by 6x^2 - ny^2 for an infinite number of integer pairs (x, y). 0
2, 4, 3, 2, 1, 0, 6, 6, 6, 6, 6, 6, 2, 6, 6, 6, 6, 6, 5, 4, 3, 2, 1, 0, 6, 6, 6, 6, 1, 6, 6, 6, 6, 6, 6, 6, 2, 6, 6, 6, 6, 6, 6, 6, 6, 2, 1, 6, 5, 4, 3, 2, 1, 0, 6, 6, 6, 6, 6, 6, 2, 6, 6, 6, 6, 6, 6, 6, 3, 6, 1, 6, 2, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 4, 3, 2, 1, 0, 6, 6, 6, 6, 1, 6, 6, 6, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

MATHEMATICA

f[n_, z_] := FindInstance[x > 0 && y > 0 && 6*x^2 - n*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, z <= 6, z = z + GCD[n, 6], fz = f[n, z]; If[fz =!= {}, Print["a(", n, ") = ", z, " {x, y} = ", {x, y} /. fz[[1]]]; Return[z]]]; a[49] := (Print["a(49) = ", 5, " {x, y} = ", {3, 1}]; 5); a[64] := (Print["a(64) = ", 6, " {x, y} = ", {49, 15}]; 6); a[101] := (Print["a(101) = ", 1, " {x, y} = ", {1875, 457}]; 1); Table[TimeConstrained[a[n], 300], {n, 1, 105}] (* Jean-Fran├žois Alcover, Oct 10 2016 *)

CROSSREFS

Sequence in context: A322398 A109158 A307500 * A123547 A123551 A286275

Adjacent sequences:  A049242 A049243 A049244 * A049246 A049247 A049248

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 10 14:50 EDT 2020. Contains 336381 sequences. (Running on oeis4.)