A087268 - OEIS

A087268

Solutions to gcd(x, pi(x)) = 1, where pi is A000720.

1, 2, 3, 5, 7, 9, 11, 12, 13, 17, 18, 19, 21, 23, 25, 26, 28, 29, 31, 32, 34, 35, 36, 37, 41, 42, 43, 45, 47, 49, 52, 53, 55, 57, 59, 60, 61, 65, 67, 68, 69, 70, 71, 73, 74, 76, 79, 81, 83, 84, 85, 86, 87, 88, 89, 91, 95, 97, 98, 99, 101, 103, 104, 106, 107, 109, 110, 111

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

EXAMPLE

All primes are included.

MATHEMATICA

Flatten[Position[Table[GCD[w, PrimePi[w]], {w, 1, 256}], 1]

PROG

(PARI) isok(n) = gcd(n, primepi(n)) == 1; \\ Michel Marcus, Apr 22 2018

CROSSREFS