A222961 Numbers n such that 2*n + {3, 5, 9, 11, 15, 21} are all primes.

1, 4, 739, 82849, 163069, 330544, 511249, 534349, 623179, 730699, 958864, 1529434, 2077954, 2109139, 2763499, 4172074, 5067199, 5882524, 5950249, 6532159, 7860409, 7880044, 9252184, 9368419, 9564769, 9605719, 10024984

Offset: 1

Author

Vincenzo Librandi, Mar 13 2013

Keywords

• nonn

Comments

After 1, a(n) is congruent to 4 or 9 (mod 10), this means that a(n) is of the form 5k-1. Clearly, each term is not divisible by 3, 7 and 11.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A136162.

Programs

Magma

[n: n in [1..11000000] | forall{2*n+k: k in [3, 5, 9, 11, 15, 21] | IsPrime(2*n+k)}];

Mathematica

Select[Range[7000000], Union[PrimeQ[2 # +{3, 5, 9, 11, 15, 21}]]=={True}&]