A020429 Numbers k such that the continued fraction for sqrt(k) has period 90.

2851, 4051, 4449, 4873, 5284, 6388, 6517, 6526, 6659, 6859, 6973, 7243, 7702, 7771, 8261, 8486, 8614, 8966, 9226, 9862, 10519, 10809, 11081, 11477, 11876, 12164, 12881, 12904, 12910, 13479, 13531, 13859, 13861, 14646, 14799, 14804, 15014, 15310, 15940

Offset

1,1

Links

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

Mathematica

cf90Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Length[ContinuedFraction[s][[2]]]] == 90]; Select[Range[16000], cf90Q] (* Harvey P. Dale, Feb 28 2023 *)

Crossrefs

Cf. A003285.

Sequence in context: A218597 A259296 A374373 * A255026 A345588 A345846

Adjacent sequences: A020426 A020427 A020428 * A020430 A020431 A020432

Keyword

nonn

Author

David W. Wilson

Status

approved