A078766 - OEIS

A078766

Number of primes less than n*phi(n).

0, 1, 3, 4, 8, 5, 13, 11, 16, 12, 29, 15, 36, 23, 30, 31, 58, 28, 68, 37, 54, 47, 96, 43, 95, 64, 92, 67, 141, 52, 158, 97, 120, 100, 146, 83, 217, 124, 158, 115, 259, 96, 279, 151, 180, 169, 326, 135, 310, 168, 258, 203, 402, 164, 327, 217, 309, 257, 480, 162, 511

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..61.

FORMULA

a(n) = A000720(A002618(n)). - Michel Marcus, Sep 27 2013

EXAMPLE

phi(3)=2 and pi(2*3)=3, hence a(3)=3

PROG

(PARI) for (n=1, 100, ep=n*eulerphi(n); pc=0; forprime (p=2, ep, pc++); print1(pc", "))

(PARI) a(n) = primepi(n*eulerphi(n)); \\ Michel Marcus, Sep 27 2013

CROSSREFS

Sequence in context: A262951 A288091 A057926 * A336840 A253080 A050417

Adjacent sequences: A078763 A078764 A078765 * A078767 A078768 A078769

KEYWORD

nonn

AUTHOR

Jon Perry, Jan 09 2003

STATUS

approved