A020393 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A020393

Numbers k such that the continued fraction for sqrt(k) has period 54.

886, 1747, 1821, 2361, 2404, 2662, 2899, 2998, 3097, 3307, 3412, 3796, 3907, 4061, 4166, 4246, 4377, 4459, 4724, 4769, 4819, 4866, 4911, 5044, 5079, 5147, 5171, 5299, 5531, 5561, 5574, 5599, 5665, 5860, 5889, 5987, 6011, 6059, 6190, 6262, 6265, 6323

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..42.

MATHEMATICA

cf54Q[n_]:=Module[{s=Sqrt[n]}, If[IntegerQ[s], 1, Length[ ContinuedFraction[ s][[2]]]]==54]; Select[Range[6400], cf54Q] (* Harvey P. Dale, Mar 24 2017 *)

CROSSREFS

Cf. A003285.

Sequence in context: A295443 A261760 A031794 * A103811 A190354 A164513

Adjacent sequences: A020390 A020391 A020392 * A020394 A020395 A020396

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved