A227230 Numbers k such that 3*2^k + {5,7} are twin primes.

1, 2, 3, 5, 6, 19, 22

Offset

1,2

Comments

No more terms up to 10^4.

Links

Table of n, a(n) for n=1..7.

Mathematica

Reap[Do[If[PrimeQ[a=3*2^n+5]&&PrimeQ[a+2], Sow[n]], {n, 150}]][[2, 1]]

Prog

(PARI) {for(k = 1, 10^4, if(ispseudoprime(a = 3*2^k + 5)&&ispseudoprime (a + 2), print1(k", ")))}

Crossrefs

Cf. A071558 Smallest k such that n*k -/+ 1 are twin primes, A181490 Numbers k such that 3*2^k -/+ 1 are twin primes.

Sequence in context: A276353 A109628 A192367 * A102977 A238335 A131599

Adjacent sequences: A227227 A227228 A227229 * A227231 A227232 A227233

Keyword

nonn,more

Author

Zak Seidov, Sep 20 2013

Status

approved