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A060967 Number of squared primes <= 2^n. 12
0, 0, 1, 1, 2, 3, 4, 5, 6, 8, 11, 14, 18, 24, 31, 42, 54, 72, 97, 128, 172, 229, 309, 418, 564, 760, 1028, 1393, 1900, 2585, 3512, 4792, 6542, 8952, 12251, 16777, 23000, 31579, 43390, 59631, 82025, 112957, 155611, 214516, 295947, 408493, 564163, 779638 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Harry J. Smith and Hiroaki Yamanouchi, Table of n, a(n) for n = 0..112, (first 64 terms from Harry J. Smith)

EXAMPLE

n=8, squared primes not exceeding 256 are 4, 9, 25, 49, 121, 169 so a(8)=6.

MATHEMATICA

Table[ PrimePi[ Floor[ 2^(g/2)//N ] ], {g, 1, 75} ]

PROG

(PARI) { f="b060967.txt"; default(primelimit, 4294965247); a=n=-1; s=1; forprime (p=2, 4294965247, a++; if (p^2>s, write(f, n++, " ", a); s*=2); if (p^2>s, write(f, n++, " ", a); s*=2); ) } \\ Harry J. Smith, Jul 15 2009

CROSSREFS

Cf. A007053, A036386.

Sequence in context: A253773 A124067 A308806 * A218930 A026483 A098131

Adjacent sequences:  A060964 A060965 A060966 * A060968 A060969 A060970

KEYWORD

nonn

AUTHOR

Labos Elemer, May 09 2001

EXTENSIONS

a(0) prepended by Harry J. Smith, Jul 15 2009

STATUS

approved

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Last modified December 7 09:33 EST 2019. Contains 329843 sequences. (Running on oeis4.)