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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A031510 Numbers n such that continued fraction for sqrt(n) has even period and central term 12. 1
146, 158, 162, 166, 178, 194, 327, 366, 372, 381, 393, 417, 429, 438, 580, 596, 604, 628, 636, 652, 668, 684, 692, 700, 716, 724, 740, 748, 764, 772, 780, 905, 945, 955, 995, 1005, 1030, 1055, 1070, 1195, 1205, 1220, 1302, 1338, 1434, 1578, 1614, 1626, 1758 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

epct12Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]] == 12]; Select[Range[2000], epct12Q] (* Harvey P. Dale, Jan 04 2015 *)

CROSSREFS

Sequence in context: A015055 A166071 A124969 * A145915 A248406 A135666

Adjacent sequences:  A031507 A031508 A031509 * A031511 A031512 A031513

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 4 21:09 EST 2016. Contains 278755 sequences.