A020418 Numbers k such that the continued fraction for sqrt(k) has period 79.

1621, 3001, 3637, 4153, 5113, 5653, 7114, 8026, 9161, 12538, 12569, 13261, 14177, 18058, 19373, 21625, 25733, 25981, 26297, 28277, 28394, 29674, 30122, 32201, 32393, 32861, 33773, 34801, 35746, 36137, 36185, 36257, 36994, 39049, 39701, 41429, 43721

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Mathematica

cf79Q[n_]:=Module[{c=Sqrt[n]}, !IntegerQ[c]&&Length[ContinuedFraction[c][[2]]]==79]; Select[Range[50000], cf79Q] (* Harvey P. Dale, Dec 23 2012 *)

Prog

(Python)
from sympy import continued_fraction_periodic
A020418_list = [n for n, s in ((i, continued_fraction_periodic(0, 1, i)[-1]) for i in range(1, 10**5)) if isinstance(s, list) and len(s) == 79] # Chai Wah Wu, Jun 08 2017

Crossrefs

Sequence in context: A269212 A269095 A269274 * A347039 A224722 A045288

Adjacent sequences: A020415 A020416 A020417 * A020419 A020420 A020421

Keyword

nonn

Author

David W. Wilson

Status

approved