A031602 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 14.

50, 1321, 2549, 2753, 4177, 4570, 6521, 6845, 12106, 15173, 15418, 19961, 23545, 26773, 27754, 28418, 28753, 29429, 31601, 31954, 32309, 32666, 33386, 33749, 34114, 34481, 35221, 36829, 40729, 41645, 42457, 45785, 46637, 47497, 48485, 51137, 53402

Offset

1,1

Links

Table of n, a(n) for n=1..37.

Mathematica

cfo14Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {}, ContinuedFraction[ s][[2]]]; len=Length[cf]; OddQ[len] && cf[[(len+1)/2]] == 14]; Select[Range[54000], cfo14Q] (* Harvey P. Dale, Dec 10 2013 *)

Crossrefs

Sequence in context: A162492 A017713 A283311 * A231743 A140520 A114251

Adjacent sequences: A031599 A031600 A031601 * A031603 A031604 A031605

Keyword

nonn

Author

David W. Wilson

Extensions

Corrected and definition clarified by Harvey P. Dale, Dec 10 2013

Status

approved