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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A031543 that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 45. 0
2027, 2039, 2047, 2063, 2083, 2087, 2091, 2099, 2111, 2123, 2131, 2143, 2147, 2179, 2187, 2191, 2203, 2207, 8104, 8168, 8192, 8200, 8256, 8296, 8320, 8352, 8384, 8448, 8480, 8488, 8512, 8544, 8552, 8576, 8584, 8608, 8704, 8736, 8744, 8800, 8832, 18231 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
cf45Q[n_]:=Module[{s=Sqrt[n], cf, len}, cf=If[IntegerQ[s], {1}, ContinuedFraction[ s][[2]]]; len=Length[cf]; EvenQ[len]&&cf[[len/2]]==45]; Select[Range[20000], cf45Q] (* Harvey P. Dale, Dec 04 2022 *)
CROSSREFS
Sequence in context: A350869 A031768 A156856 * A031723 A145721 A103126
KEYWORD
nonn
AUTHOR
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 27 16:21 EST 2024. Contains 370378 sequences. (Running on oeis4.)