A031548 Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 50.

2502, 2514, 2518, 2542, 2546, 2558, 2566, 2578, 2582, 2594, 2606, 2614, 2638, 2654, 2658, 2662, 2686, 2694, 2702, 5628, 5637, 5673, 5691, 5694, 5721, 5793, 5799, 5817, 5844, 5853, 5871, 5889, 5937, 5961, 5979, 5982, 5988, 5997, 6009, 6033, 6081, 10004

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Mathematica

ct50Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {0}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&& cf[[len/2]] == 50]; Select[Range[11000], ct50Q] (* Harvey P. Dale, May 10 2015 *)

Crossrefs

Sequence in context: A120408 A031778 A031688 * A045216 A205175 A205274

Adjacent sequences: A031545 A031546 A031547 * A031549 A031550 A031551

Keyword

nonn

Author

David W. Wilson

Status

approved