A107196 - OEIS

A107196

Primes of the form 4x^2 + 21y^2.

37, 193, 277, 421, 541, 673, 1009, 1033, 1093, 1129, 1201, 1213, 1429, 1549, 1621, 1789, 1801, 2053, 2137, 2377, 2473, 2521, 2557, 2689, 2797, 2857, 3217, 3229, 3301, 3529, 3613, 3637, 3697, 3733, 3889, 4201, 4621, 4657, 4729, 4789, 4813

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Discriminant = -336. See A107132 for more information.

LINKS

Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]

N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

MATHEMATICA

QuadPrimes2[4, 0, 21, 10000] (* see A106856 *)

PROG

(PARI) list(lim)=my(v=List(), w, t); for(x=1, sqrtint(lim\4), w=4*x^2; for(y=1, sqrtint((lim-w)\21), if(isprime(t=w+21*y^2), listput(v, t)))); Set(v) \\ Charles R Greathouse IV, Feb 10 2017

CROSSREFS

Sequence in context: A137724 A172080 A142181 * A140027 A109320 A221571

Adjacent sequences: A107193 A107194 A107195 * A107197 A107198 A107199

KEYWORD

nonn,easy

AUTHOR

T. D. Noe, May 13 2005

STATUS

approved