A020354 Numbers k such that the continued fraction for sqrt(k) has period 15.

109, 353, 461, 617, 685, 709, 877, 1066, 1097, 1241, 1466, 1553, 1877, 2290, 2545, 2713, 2738, 2858, 3077, 3314, 3562, 3653, 4498, 4538, 4570, 4573, 5365, 5557, 5578, 5906, 6409, 6682, 7082, 7085, 7090, 7481, 7825, 8005, 8381, 8794, 8945, 9049, 9389

Offset

1,1

Links

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

Mathematica

q[k_] := Module[{c = ContinuedFraction[Sqrt[k]]}, Length[c] == 2 && Length[c[[2]]] == 15]; Select[Range[10000], q] (* Amiram Eldar, Aug 21 2025 *)

Crossrefs

Sequence in context: A238682 A070180 A107198 * A142846 A166560 A139644

Adjacent sequences: A020351 A020352 A020353 * A020355 A020356 A020357

Keyword

nonn

Author

David W. Wilson

Status

approved