A095967 Numbers n such that r3(k) * 2^n + 1 is prime, where r3() = A002277 and k is the number of decimal digits of 2^n.

1, 2, 6, 9, 20, 46, 58, 64, 69, 110, 158, 178, 186, 268, 424, 624, 641, 1236, 1593, 2264, 2870, 5797, 7518, 7688, 9300

Offset

1,2

Comments

a(1) through a(25) have been proved to be prime with WinPFGW. a(25) has 5600 digits. No more terms up to 12800.

Results were computed using the PrimeFormGW (PFGW) primality-testing program. - Hugo Pfoertner, Nov 14 2019

Links

Table of n, a(n) for n=1..25.

Example

a(4)=9 because 333 * 2^9 + 1 = 170497, a prime.

Crossrefs

Sequence in context: A265016 A279897 A336131 * A316429 A337639 A047161

Adjacent sequences: A095964 A095965 A095966 * A095968 A095969 A095970

Keyword

more,nonn,base

Author

Jason Earls, Jul 15 2004

Status

approved