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A020423 Numbers n such that continued fraction for sqrt(n) has period 84. 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 22 17:02 EDT 2019. Contains 325225 sequences. (Running on oeis4.)