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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130230 Primes p == 5 (mod 8) such that the Diophantine equation x^2 - p*y^2 = -4 has a solution in odd integers x, y. 1
5, 13, 29, 53, 61, 109, 149, 157, 173, 181, 229, 277, 293, 317, 397, 421, 461, 509, 541, 613, 653, 661, 733, 773, 797, 821, 853, 941, 1013, 1021, 1061, 1069, 1093, 1109, 1117, 1181, 1229, 1237, 1277, 1373, 1381, 1429, 1453, 1493, 1549, 1597 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the Diophantine equation x^2 - p*y^2 = -4 to have a solution in odd integers x, y we must have p == 5 (mod 8)

Calculated using Dario Alpern's quadratic Diophantine solver at http://www.alpertron.com.ar/QUAD.HTM

Suggested by a discussion on the Number Theory Mailing List, circa Aug 01 2007.

LINKS

Table of n, a(n) for n=1..46.

CROSSREFS

Cf. A130229.

Sequence in context: A194270 A194700 A220500 * A106931 A078370 A247903

Adjacent sequences:  A130227 A130228 A130229 * A130231 A130232 A130233

KEYWORD

nonn

AUTHOR

Warut Roonguthai, Aug 06 2007

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 March 26 16:55 EDT 2019. Contains 321510 sequences. (Running on oeis4.)