

A152783


Values of p for which 2^p  1 is prime and which are followed by a gap such that no 2^q  1 is prime for p < q < 2*p.


0




OFFSET

1,1


LINKS

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


FORMULA

{A000043(i): A134458(i) >= A000043(i)}.  R. J. Mathar, Dec 20 2008


EXAMPLE

127 is in this sequence because 2^1271 is prime, but no value of 2^q1 is prime for q > 127 and q <= 254. (The next value of q to yield a prime is 521 and is outside the (127,254] interval.)


MATHEMATICA

s={}; Do[If[MersennePrimeExponent[k+1] > 2 * MersennePrimeExponent[k], AppendTo[s, MersennePrimeExponent[k]]], {k, 1, 44}]; s (* Amiram Eldar, Feb 03 2019 *)


CROSSREFS

Cf. A000043, A134458.
Sequence in context: A096523 A299132 A142736 * A299890 A200813 A332574
Adjacent sequences: A152780 A152781 A152782 * A152784 A152785 A152786


KEYWORD

nonn,more


AUTHOR

J. Lowell, Dec 12 2008


EXTENSIONS

Edited by R. J. Mathar, Dec 20 2008
a(5) inserted by Amiram Eldar, Feb 03 2019


STATUS

approved



