A020381 Numbers k such that the continued fraction for sqrt(k) has period 42.

571, 724, 889, 907, 1081, 1348, 1477, 1576, 1619, 1633, 1636, 1732, 1786, 1841, 2073, 2167, 2253, 2276, 2339, 2344, 2433, 2493, 2518, 2611, 2819, 2821, 2896, 2901, 2939, 3039, 3070, 3142, 3154, 3203, 3284, 3430, 3439, 3467, 3513, 3523, 3546, 3556, 3573

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

cf42Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Length[ ContinuedFraction[ s][[2]]]]==42]; Select[Range[4000], cf42Q] (* Harvey P. Dale, Sep 24 2019 *)

Crossrefs

Cf. A003285.

Sequence in context: A268248 A246229 A073036 * A142767 A251384 A076465

Adjacent sequences: A020378 A020379 A020380 * A020382 A020383 A020384

Keyword

nonn

Author

David W. Wilson

Status

approved