A087266 a(n) = gcd(2^n, pi(2^n)) = gcd(A000079(n), A007053(n)).

1, 2, 4, 2, 1, 2, 1, 2, 1, 4, 1, 4, 4, 4, 8, 2, 1, 8, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 4, 1, 1, 2, 1, 1, 1, 4, 4, 2, 4, 4, 1, 1, 4, 2, 1, 1, 2, 2, 1, 8, 1, 4, 16, 1, 2, 4, 2, 4, 2, 1, 1, 8, 1, 4, 1, 1, 2, 16, 1, 1, 1, 1, 4, 1, 1, 4, 8, 1, 4, 4, 8, 4, 4, 2, 1, 1, 2, 4, 8, 16, 2

Offset

1,2

Links

Table of n, a(n) for n=1..92.

Mathematica

Table[GCD[2^n, PrimePi[2^n]], {n, 40}] (* Michael De Vlieger, Mar 25 2017 *)

Prog

(PARI) a(n) = gcd(2^n, primepi(2^n)); \\ Michel Marcus, Mar 26 2017

Crossrefs

Cf. A000720, A007053.

Sequence in context: A342060 A302828 A321622 * A160801 A177002 A079046

Adjacent sequences: A087263 A087264 A087265 * A087267 A087268 A087269

Keyword

nonn

Author

Labos Elemer, Sep 16 2003

Extensions

a(53)-a(92) from Amiram Eldar, Jun 09 2024

Status

approved