A031635 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 47.

45877, 95033, 96269, 126961, 128389, 129106, 160289, 162698, 201065, 204665, 206477, 250441, 294293, 300833, 303029, 346369, 347546, 349906, 351089, 355841, 357034, 358229, 359426, 468697, 474185, 535322, 536785, 538250, 541186, 544130

Offset

1,1

Links

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

Mathematica

opct47Q[n_]:=Module[{sqrt=Sqrt[n], cf, len}, cf=If[IntegerQ[sqrt], {}, ContinuedFraction[sqrt][[2]]]; len=Length[cf]; OddQ[len] && cf[[Floor[len/2]+1]] == 47] (* Harvey P. Dale, Sep 19 2012 *)

Crossrefs

Sequence in context: A257358 A232255 A031841 * A159725 A210306 A223368

Adjacent sequences: A031632 A031633 A031634 * A031636 A031637 A031638

Keyword

nonn

Author

David W. Wilson

Extensions

Corrected by Harvey P. Dale, Sep 19 2012

Status

approved