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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A097700 Numbers not of form x^2 + 2y^2. 10
5, 7, 10, 13, 14, 15, 20, 21, 23, 26, 28, 29, 30, 31, 35, 37, 39, 40, 42, 45, 46, 47, 52, 53, 55, 56, 58, 60, 61, 62, 63, 65, 69, 70, 71, 74, 77, 78, 79, 80, 84, 85, 87, 90, 91, 92, 93, 94, 95, 101, 103, 104, 105, 106, 109, 110, 111, 112, 115, 116, 117, 119, 120, 122 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Is lim_{n->inf} a(n)/n = 3/4?

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..6800

MATHEMATICA

formQ[n_]:=Reduce[x>=0&&y>=0&&n==x^2 + 2 y^2, {x, y}, Integers]==False; Select[Range[0, 200], formQ] (* Vincenzo Librandi, Jan 15 2017 *)

PROG

(MAGMA) [n: n in [0..160] | NormEquation(2, n) eq false]; // Vincenzo Librandi, Jan 15 2017

CROSSREFS

Complement of A002479.

Sequence in context: A066513 A218852 A028810 * A172321 A154689 A175766

Adjacent sequences:  A097697 A097698 A097699 * A097701 A097702 A097703

KEYWORD

nonn

AUTHOR

Ralf Stephan, Aug 23 2004

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 August 3 08:21 EDT 2021. Contains 346435 sequences. (Running on oeis4.)