

A036378


Number of primes p between powers of 2, 2^n < p <= 2^(n+1).


98



1, 1, 2, 2, 5, 7, 13, 23, 43, 75, 137, 255, 464, 872, 1612, 3030, 5709, 10749, 20390, 38635, 73586, 140336, 268216, 513708, 985818, 1894120, 3645744, 7027290, 13561907, 26207278, 50697537, 98182656, 190335585, 369323305, 717267168, 1394192236
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OFFSET

0,3


COMMENTS

Number of primes whose binary order (A029837) is n, i.e. those with ceiling[ Log[ 2,p ] ] = n.
First differences of A007053. This sequence illustrates how far the Bertrand postulate is over satisfied.
Scaled for Ramanujan primes as in A190501, A190502.
This sequence appears complete such that any nonnegative number can be written as a sum of distinct terms of this sequence. The sequence has been checked for completeness up to the gap between 2^46 and 2^47. Assuming that after 2^46 the formula x/log(x) is a good approximation to primepi(x), it can be proved that 2*a(n) > a(n+1) for all n >= 46, which is a sufficient condition for completeness. [Frank M Jackson, Feb 02 2012]


LINKS

T. D. Noe, Table of n, a(n) for n=0..74 (using data from A007053)
P. D. Beale, A new class of scalable parallel pseudorandom number generators based on PohligHellman exponentiation ciphers, arXiv:1411.2484 [physics.compph], 20142015.
SeungHoon Lee, Mario Gerla, Hugo Krawczyk, KangWon Lee, and Elizabeth A. Quaglia, Performance Evaluation of Secure Network Coding using Homomorphic Signature.
Index entries for sequences related to occurrences of various subsets of primes in range ]2^n,2^(n+1)]


FORMULA

a(n) = primepi(2^(n+1))primepi(2^n).
a(n) = A095005(n)+A095006(n) = A095007(n) + A095008(n) = A095013(n) + A095014(n) = A095015(n) + A095016(n) (for n > 1) = A095021(n)+A095022(n)+A095023(n)+A095024(n) = A095019(n)+A095054(n) = A095020(n)+A095055(n) = A095060(n)+A095061(n) = A095063(n)+A095064(n) = A095094(n)+A095095(n).


EXAMPLE

The 7 primes for which A029837(p)=6 are 37,41,43,47,53,59,61.


MATHEMATICA

t = Table[PrimePi[2^n], {n, 0, 20}]; Rest@t  Most@t (* Robert G. Wilson v, Mar 20 2006 *)


PROG

(PARI) a(n) = primepi(1<<(n+1))primepi(1<<n)
(MAGMA) [1, 1] cat [#PrimesInInterval(2^n, 2^(n+1)): n in [2..29]]; // Vincenzo Librandi, Nov 18 2014


CROSSREFS

Cf. A000720, A190501, A190502, A190568, A007053.
Sequence in context: A095333 A095326 A095330 * A265813 A259864 A028303
Adjacent sequences: A036375 A036376 A036377 * A036379 A036380 A036381


KEYWORD

nonn


AUTHOR

Labos Elemer


EXTENSIONS

More terms from Labos Elemer, May 13 2004
Entries checked by Robert G. Wilson v, Mar 20 2006


STATUS

approved



