

A099439


Numbers k such that A000295(k) = 2^kk1 is prime.


5



4, 10, 14, 16, 26, 50, 56, 70, 116, 2072, 6250, 13670, 14216, 14626, 396128
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OFFSET

1,1


COMMENTS

The next term is > 400000.
Equals A063791 + 1.  Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008
Some of the results were computed using the PrimeFormGW (PFGW) primalitytesting program.  Hugo Pfoertner, Nov 14 2019


LINKS

Table of n, a(n) for n=1..15.


EXAMPLE

a(1) = 4 because 2^4  4  1 = 11 is prime.


CROSSREFS

Cf. A000295 (2^nn1), A099440 (primes in A000295), A099441 (2^nn1 is a semiprime), A099442 (semiprimes in A000295).
Sequence in context: A310361 A310362 A310363 * A310364 A310365 A310366
Adjacent sequences: A099436 A099437 A099438 * A099440 A099441 A099442


KEYWORD

nonn,more,hard


AUTHOR

Hugo Pfoertner, Oct 18 2004


EXTENSIONS

a(15) (a PRP) from Karsten Bonath, Jun 07 2018


STATUS

approved



