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A049246 Smallest nonnegative value taken on by 7x^2 - ny^2 for an infinite number of integer pairs (x, y). 0
3, 5, 1, 3, 2, 1, 0, 7, 7, 2, 7, 4, 2, 7, 3, 7, 7, 7, 1, 7, 7, 6, 5, 4, 3, 2, 1, 0, 7, 7, 1, 7, 7, 7, 7, 7, 3, 1, 7, 7, 7, 7, 3, 7, 7, 7, 1, 7, 7, 7, 3, 7, 7, 1, 7, 7, 6, 5, 1, 3, 2, 1, 0, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 4, 7, 7, 3, 7, 7, 7, 1, 7, 3, 7, 1, 7, 7, 7, 7, 7, 7, 1, 5, 7, 7, 7, 7, 3, 2, 6, 1, 7, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

p = 7; f[n_, z_] := FindInstance[x > 0 && y > 0 && p*x^2 - n*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, z <= p, z = z + GCD[n, p], Switch[n, 64 | 81, z = p; fz = $Aborted, _, fz = TimeConstrained[f[n, z], 300]]; fz = If[fz === $Aborted, {{x -> Null, y -> Null}}, fz]; If[fz =!= {}, Print["a(", n, ") = ", z, " {x, y} = ", {x, y} /. fz[[1]]]; Return[z]]]; Table[a[n], {n, 1, 105}] (* Jean-Fran├žois Alcover, Oct 11 2016 *)

CROSSREFS

Sequence in context: A127250 A230407 A137759 * A231186 A021078 A130793

Adjacent sequences:  A049243 A049244 A049245 * A049247 A049248 A049249

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified July 4 15:25 EDT 2020. Contains 335448 sequences. (Running on oeis4.)