A060967 Number of squared primes <= 2^n.

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

Offset

0,5

Links

Ray Chandler, Table of n, a(n) for n = 0..125 (terms 0..63 from Harry J. Smith, terms 64..112 from Hiroaki Yamanouchi)

Formula

a(2*n) = A007053(n). - Amiram Eldar, Jul 10 2024

Example

For n = 8, the 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) a(n) = { primepi(sqrtint(2^n)) } \\ Harry J. Smith, Jul 15 2009

Crossrefs

Cf. A007053, A036386.

Sequence in context: A253773 A124067 A308806 * A218930 A350391 A026483

Adjacent sequences: A060964 A060965 A060966 * A060968 A060969 A060970

Keyword

nonn,changed

Author

Labos Elemer, May 09 2001

Extensions

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

Status

approved