A020428 Numbers k such that the continued fraction for sqrt(k) has period 89.

2389, 3613, 4129, 4957, 5689, 7121, 7841, 7901, 8377, 8506, 9529, 10529, 12689, 13369, 13402, 13465, 14057, 15049, 15269, 16529, 19729, 20122, 21881, 22186, 23257, 23425, 24961, 27409, 28433, 29101, 30497, 31765, 31945, 32573, 35009, 35173, 36298

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]]] == 89]; Select[Range[37000], q] (* Amiram Eldar, Aug 25 2025 *)

Crossrefs

Cf. A003285.

Sequence in context: A172772 A172841 A172752 * A253422 A100974 A279538

Adjacent sequences: A020425 A020426 A020427 * A020429 A020430 A020431

Keyword

nonn

Author

David W. Wilson

Status

approved