A095967 - OEIS

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

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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

EXAMPLE

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

CROSSREFS

KEYWORD

more,nonn,base

AUTHOR

Jason Earls, Jul 15 2004

STATUS

approved