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A192064 Number of primes in the range [2^n-n, 2^n]. 2
0, 1, 2, 2, 1, 2, 2, 1, 1, 2, 2, 1, 2, 2, 1, 0, 1, 3, 3, 2, 3, 3, 2, 2, 2, 0, 1, 0, 0, 1, 0, 2, 2, 2, 0, 1, 3, 2, 0, 2, 0, 2, 3, 0, 1, 0, 1, 0, 0, 0, 2, 0, 1, 0, 2, 1, 3, 3, 2, 1, 0, 3, 1, 1, 1, 1, 2, 5, 1, 1, 1, 0, 0, 1, 3, 0, 2, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..78.

EXAMPLE

a(0)=0 because [2^0-0, 2^0]=[1, 1],

a(1)=1 because 2 in range [2^1-1, 2^1]=[1,2],

a(2)=2 because 2, 3 in range [2^2-2, 2^2]=[2, 4],

a(3)=2 because 5, 7 in range [2^3-3, 2^3]=[5, 8],

a(4)=1 because 13 in range [2^4-4, 2^4]=[12, 16],

a(5)=2 because 29, 31 in range [2^5-5, 2^5]=[27, 32].

MAPLE

A192064 := proc(n) numtheory[pi](2^n)-numtheory[pi](2^n-n-1) ; end proc: # R. J. Mathar, Jul 07 2011

PROG

(PARI) a(n)=sum(k=2^n-n, 2^n, isprime(k)) \\ Charles R Greathouse IV, Jul 03 2011

CROSSREFS

Sequence in context: A232628 A087889 A285110 * A225182 A014710 A055174

Adjacent sequences:  A192061 A192062 A192063 * A192065 A192066 A192067

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jul 03 2011

EXTENSIONS

Corrected and extended by Charles R Greathouse IV, Jul 03 2011

STATUS

approved

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Last modified December 13 09:05 EST 2017. Contains 295957 sequences.