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A036378 Number of primes p between powers of 2, 2^n < p <= 2^(n+1). 94
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 (list; graph; refs; listen; history; text; internal format)
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 Pohlig-Hellman exponentiation ciphers, arXiv:1411.2484 [physics.comp-ph], 2014-2015.

Seung-Hoon Lee, Mario Gerla, Hugo Krawczyk, Kang-Won 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)-primepi(2^(n-1)).

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)-primepi(1<<(n-1))

(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

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Last modified May 26 09:12 EDT 2017. Contains 287093 sequences.