A321353 Numbers k such that 3*2^k - 25 is prime.

4, 5, 6, 7, 8, 9, 12, 13, 16, 17, 18, 21, 23, 29, 31, 33, 35, 36, 41, 58, 63, 66, 69, 82, 96, 99, 148, 157, 175, 196, 241, 267, 349, 394, 404, 414, 435, 456, 485, 498, 537, 548, 584, 715, 727, 765, 929, 1007, 1076, 1399, 1619, 1652, 1715, 2758, 3039, 3131, 3773, 3822, 5001

Offset

1,1

Comments

Appears (at least initially) to contain more primes that the analogous sequences for 2^k-1 or 2^k-3. Compare the comment of Paul Bourdelais in A050414.

Links

Table of n, a(n) for n=1..59.

Example

7 is a term, because 3*2^7 - 25 = 359 is prime.

Mathematica

Select[Range[100], PrimeQ[3 2^# - 25] &]

Prog

(PARI) for(n=0, 2000, if(ispseudoprime(p=3*2^n-25), print1(n, ", ")));

Crossrefs

Cf. A050414.

Sequence in context: A047569 A039062 A067187 * A161674 A285623 A213518

Adjacent sequences: A321350 A321351 A321352 * A321354 A321355 A321356

Keyword

nonn

Author

Gilbert Mozzo, Nov 07 2018

Status

approved