A247260 Numbers n such that 5*6^n + 1 is prime.

1, 2, 4, 17, 136, 147, 203, 590, 754, 964, 970, 1847, 2031, 2727, 2871, 5442, 7035, 7266, 11230, 23307, 27795, 34152, 42614, 127206, 133086

Offset: 1

Author

Robert Price, Sep 10 2014

Keywords

• nonn
• hard
• more

Comments

a(26) > 2*10^5.

Crossrefs

Cf. A079906.

Programs

Mathematica

Do[ If[ PrimeQ[5*6^n + 1], Print[n]], {n, 0, 200000}]

PARI

for(n=0,2*10^5,if(ispseudoprime(5*6^n+1),print1(n,", "))) \\ Derek Orr, Sep 10 2014