login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

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 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A229848 Values of n such that the equation x^2 - 3*n*y^2 = n has integer solutions. 1
1, 4, 7, 9, 13, 16, 19, 25, 28, 31, 36, 37, 43, 49, 52, 61, 63, 64, 67, 76, 79, 81, 91, 100, 103, 109, 112, 117, 121, 124, 127, 139, 144, 148, 151, 157, 163, 169, 171, 172, 175, 181, 193, 196, 199, 208, 211, 217, 223, 225, 229, 244, 247, 252, 256, 268, 271 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

37 appears in the sequence because the equation x^2 - 111*y^2 = 37 has integer solutions.

MATHEMATICA

Select[Range[300], Length[FullSimplify[Solve[x^2-3*#*y^2==#, {x, y}, Integers]/.C[1]->1]]>0&] (* Vaclav Kotesovec, Oct 08 2013 *)

CROSSREFS

Cf. A172000, A227939

Sequence in context: A108287 A230240 A243175 * A239993 A332335 A310961

Adjacent sequences:  A229845 A229846 A229847 * A229849 A229850 A229851

KEYWORD

nonn

AUTHOR

Colin Barker, Oct 07 2013

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 November 30 17:12 EST 2021. Contains 349424 sequences. (Running on oeis4.)