login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A020418 Numbers n such that continued fraction for sqrt(n) has period 79. 1
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 (list; graph; refs; listen; history; text; internal format)
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 * A224722 A045288 A204726

Adjacent sequences:  A020415 A020416 A020417 * A020419 A020420 A020421

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 21 14:18 EDT 2019. Contains 328301 sequences. (Running on oeis4.)