A049270 - OEIS

A049270

Smallest nonnegative value taken on by nx^2 - 11y^2 for an infinite number of integer pairs (x, y).

1, 2, 1, 1, 1, 6, 7, 8, 9, 10, 0, 1, 2, 3, 1, 4, 6, 7, 8, 4, 10, 11, 1, 13, 1, 5, 1, 13, 2, 19, 1, 13, 22, 5, 19, 9, 1, 3, 7, 29, 6, 31, 32, 0, 1, 2, 1, 4, 5, 6, 7, 8, 1, 10, 11, 5, 13, 14, 1, 1, 2, 2, 7, 5, 6, 22, 1, 17, 1, 5, 1, 13, 13, 7, 1, 13, 33, 34, 7, 16, 25, 22, 8, 13, 10, 3, 19, 44, 1

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..89.

MATHEMATICA

f[n_, z_] := FindInstance[x > 0 && y > 0 && n*x^2 - 11*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, True, z = z + GCD[n, 11], fz = f[n, z]; If[fz =!= {}, Print["a(", n, ") = ", z, " {x, y} = ", {x, y} /. fz[[1]]]; Return[z]]]; Array[a, 89] (* Jean-François Alcover, Oct 09 2016 *)

CROSSREFS

Sequence in context: A325970 A347781 A088152 * A025269 A265656 A137296

Adjacent sequences: A049267 A049268 A049269 * A049271 A049272 A049273

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved