A020423 Numbers k such that the continued fraction for sqrt(k) has period 84.

1831, 1999, 2149, 2791, 3292, 4126, 4237, 4393, 4639, 4897, 5121, 5279, 5534, 5971, 5996, 6621, 6729, 7209, 7214, 7661, 7737, 8014, 8129, 8251, 8361, 8457, 8577, 8674, 8812, 8817, 8947, 9356, 9376, 9469, 9541, 9753, 10063, 10113, 10487, 11157, 11229

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Mathematica

cf84Q[n_] := Module[{s = Sqrt[n], c}, c = If[IntegerQ[s], {1}, ContinuedFraction[s][[2]]]; Length[c] == 84]; Select[Range[12000], cf84Q] (* Harvey P. Dale, Nov 03 2015 *)

Crossrefs

Sequence in context: A196895 A151644 A031934 * A031804 A054813 A320720

Adjacent sequences: A020420 A020421 A020422 * A020424 A020425 A020426

Keyword

nonn

Author

David W. Wilson

Status

approved