A020380 - OEIS

A020380

Numbers k such that the continued fraction for sqrt(k) has period 41.

1117, 1657, 2965, 3209, 3385, 3418, 3449, 3917, 3985, 4306, 4537, 4721, 5594, 5717, 5897, 6817, 7978, 8458, 8917, 9125, 9437, 10685, 11441, 12074, 12634, 12805, 13498, 14866, 15101, 15413, 15482, 16106, 16525, 16565, 16570, 18149, 18233, 18394, 18925

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..39.

MATHEMATICA

cfp41Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Length[ ContinuedFraction[s][[2]]]]==41]; Select[Range[20000], cfp41Q] (* Harvey P. Dale, Jan 28 2017 *)

CROSSREFS

Cf. A003285.

Sequence in context: A258691 A221428 A161848 * A243527 A251360 A201034

Adjacent sequences: A020377 A020378 A020379 * A020381 A020382 A020383

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved