A124855 Numbers k such that 3k + 4 and 4k + 3 are primes.

1, 5, 11, 19, 25, 31, 41, 49, 59, 65, 89, 91, 109, 115, 121, 125, 151, 161, 179, 181, 205, 209, 229, 241, 245, 275, 305, 329, 331, 349, 355, 361, 371, 389, 415, 439, 509, 515, 521, 535, 551, 595, 599, 625, 661, 665, 671, 719, 725, 749, 755, 769, 779, 791, 839

Offset

1,2

Links

Table of n, a(n) for n=1..55.

Mathematica

Select[Range[850], PrimeQ[3# + 4] && PrimeQ[4# + 3] &] (* Ray Chandler, May 11 2007 *)

Prog

(Magma) [n: n in [0..1000] | IsPrime(3*n+4) and IsPrime(4*n+3)]; // Vincenzo Librandi, Mar 26 2010
(Python)
from sympy import isprime
def isA124855(n): return isprime(3*n+4) and isprime(4*n+3) # Aidan Chen, Feb 03 2026

Crossrefs

Intersection of A034936 and A095278. Prime terms are in A106068.

Sequence in context: A117089 A356140 A114269 * A286690 A363637 A190756

Adjacent sequences: A124852 A124853 A124854 * A124856 A124857 A124858

Keyword

nonn

Author

Zak Seidov, Nov 10 2006

Status

approved