A108249 Consider primes p and q such that p = 3^k + 20 and q = 3^(k+1) + 20 for some k; sequence gives values of p.

23, 29, 47, 101, 2207, 59069

Offset

1,1

Comments

No additional terms through k=5000. - Harvey P. Dale, Jun 12 2025

Links

Table of n, a(n) for n=1..6.

Example

3^1 + 20 = 23, 3^2 + 20 = 29.

Mathematica

Select[Partition[Table[3^k+20, {k, 50}], 2, 1], AllTrue[#, PrimeQ]&][[;; , 1]] (* Harvey P. Dale, Jun 12 2025 *)

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(y", ") ) ) }

Crossrefs

Cf. A108258.

Sequence in context: A108111 A085713 A102904 * A338324 A232725 A045120

Adjacent sequences: A108246 A108247 A108248 * A108250 A108251 A108252

Keyword

nonn

Author

Cino Hilliard, Jun 29 2005

Status

approved