A064449 a(n) = gcd(Phi(n!), Phi(n^n), Phi(lcm(1..n))).

1, 1, 2, 4, 4, 16, 6, 64, 18, 64, 10, 1152, 12, 1536, 1080, 1024, 16, 442368, 18, 163840, 972, 163840, 22, 15925248, 100, 196608, 1458, 196608, 28, 4777574400, 30, 1048576, 481140, 1048576, 21000, 2293235712, 36, 37748736, 157464, 524288000

Offset

1,3

Links

Harry J. Smith, Table of n, a(n) for n = 1..300

Formula

a(n) = gcd(A000010(A000142(n)), A000010(A000312(n)), A000010(A003418(n))).

Example

n=6: a(6) = gcd(Phi(720), Phi(46656), Phi(60)) = gcd(192, 16, 15552) = 16.

Prog

(PARI) { L=1; for (n=1, 300, L=lcm(L, n); write("b064449.txt", n, " ", gcd(eulerphi(n!), gcd(eulerphi(n^n), eulerphi(L)))) ) } \\ Harry J. Smith, Sep 14 2009

Crossrefs

Cf. A000010, A000142, A000312, A003418.

Sequence in context: A077815 A218075 A366709 * A117291 A246047 A079102

Adjacent sequences: A064446 A064447 A064448 * A064450 A064451 A064452

Keyword

nonn

Author

Labos Elemer, Oct 02 2001

Status

approved