A108259 Consider primes p and q such that p = 3^k + 2 and q = 3^(k+1) + 2 for some k; sequence gives values of p.

3, 5, 11, 29, 4782971

Offset

1,1

Comments

a(6) > 3^1400000 + 2, if it exists (cf. A051783). - Amiram Eldar, Jul 07 2024

Links

Table of n, a(n) for n=1..5.

Example

3^1 + 2 = 5, 3^2 + 2 = 11.

Mathematica

3^#+2&/@Select[Range[0, 20], AllTrue[{3^#+2, 3^(#+1)+2}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Nov 01 2015 *)

Prog

(PARI) g(m, n, b) = { for(x=0, n, y=m+b^x+b%2; z=m+b^(x+1)+b%2; if(isprime(y)&isprime(z), print1(p", ") ) ) }

Crossrefs

Cf. A051783.

Sequence in context: A146243 A262936 A214089 * A093933 A165572 A246901

Adjacent sequences: A108256 A108257 A108258 * A108260 A108261 A108262

Keyword

nonn

Author

Cino Hilliard, Jun 29 2005

Extensions

Offset corrected by Amiram Eldar, Jul 07 2024

Status

approved