A031650 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 62.

48449, 78481, 80170, 117085, 118457, 217381, 218314, 223009, 279073, 281189, 284378, 286514, 348461, 350825, 357965, 425545, 511754, 514618, 516053, 518929, 521813, 602801, 605909, 607466, 612149, 618421, 619994, 709693, 719833, 723229

Offset

1,1

Links

Table of n, a(n) for n=1..30.

Mathematica

cf62Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1, 1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len]&&cf[[(len+1)/2]] == 62]; Select[Range[724000], cf62Q] (* Harvey P. Dale, Jun 21 2020 *)

Crossrefs

Sequence in context: A151839 A151876 A083627 * A223935 A278020 A237105

Adjacent sequences: A031647 A031648 A031649 * A031651 A031652 A031653

Keyword

nonn

Author

David W. Wilson

Extensions

First term 3845 removed by Georg Fischer, Jun 16 2019

Status

approved