A263310 Numbers n such that p=6*n+1, q=6*p+1 and r=6*q+1 are primes.

10, 25, 55, 61, 101, 125, 156, 220, 221, 381, 391, 465, 475, 495, 576, 810, 891, 901, 975, 1060, 1145, 1396, 1430, 1630, 1650, 1726, 1795, 1811, 1881, 1885, 1915, 2196, 2265, 2335, 2391, 2405, 2456, 2536, 2575, 2636, 2651, 2820, 2911, 2915, 2951, 2965, 3051, 3211, 3245, 3335

Offset: 1

Author

Zak Seidov, Oct 13 2015

Keywords

• nonn

Comments

Subsequence of A263309 (and as such also of A024899).

Crossrefs

Cf. A024899, A263309.

Programs

Maple

isA263310 := proc(n)
    return isprime(6*n+1) and isprime(36*n+7) and isprime(216*n+43) ;
end proc:
for n from 1 to 3000 do
    if isA263310(n) then
        printf("%d,",n);
    end if;
end do: # R. J. Mathar, Oct 17 2015

Mathematica

Select[Range[10000],PrimeQ[p=6*#+1]&& PrimeQ[q=6*p+1]&& PrimeQ[r=6*q+1]&]

PARI

for(n=1, 1e4, if(isprime(p=6*n+1)&&isprime(q=6*p+1)&&isprime(6*q+1), print1(n", "))) \\ Altug Alkan, Oct 17 2015