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A031548 Numbers k such that the continued fraction for sqrt(k) has even period and central term 50. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 28 07:31 EDT 2021. Contains 346319 sequences. (Running on oeis4.)