A031620 Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 32.

13274, 21106, 21397, 21985, 44269, 58789, 75914, 77573, 78689, 93997, 96461, 114685, 116041, 118777, 120157, 139658, 143413, 162229, 163034, 163841, 167906, 169546, 170369, 196093, 219865, 227417, 229325, 249962, 250961, 252965, 253970

Offset

1,1

Links

Table of n, a(n) for n=1..31.

Mathematica

cf32Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len]&&cf[[Floor[len/2]]]==cf[[Ceiling[len/2]]] == 32]; Select[ Range[254000], cf32Q] (* Harvey P. Dale, May 01 2022 *)

Crossrefs

Subsequence of A003814.

Sequence in context: A184001 A345583 A345840 * A251339 A318252 A034625

Adjacent sequences: A031617 A031618 A031619 * A031621 A031622 A031623

Keyword

nonn

Author

David W. Wilson

Extensions

First term 1025 removed by Georg Fischer, Jun 16 2019

Status

approved