A031788 Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 20 ones.

478, 669, 724, 751, 766, 889, 958, 1289, 1318, 1409, 1499, 1531, 1576, 1589, 1669, 1709, 1713, 1732, 1738, 1753, 1783, 1828, 1829, 1873, 1933, 1969, 2059, 2073, 2095, 2169, 2185, 2188, 2287, 2317, 2321, 2391, 2395, 2433, 2506, 2572, 2588, 2634, 2656

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 && Count[c[[2]], 1] == 20]; Select[Range[3000], q] (* Amiram Eldar, Aug 10 2025 *)

Crossrefs

Sequence in context: A261816 A352265 A020375 * A252543 A235083 A252544

Adjacent sequences: A031785 A031786 A031787 * A031789 A031790 A031791

Keyword

nonn

Author

David W. Wilson

Status

approved