A066909 - OEIS

%I #21 May 11 2024 16:18:39

%S 0,1,2,3,1,5,2,1,7,1,1,1,9,3,7,7,8,17,18,9,16,15,15,1,24,1,26,13,17,1,

%T 19,9,14,23,3,23,11,31,19,1,6,37,26,21,7,45,35,35,25,41,2,17,27,1,31,

%U 43,50,41,15,49,55,9,10,51,28,37,30,13,26,47,24,13,28,27,73,73,76,43,4

%N (product of primes < n that do not divide n) (mod n).

%H John Tyler Rascoe, <a href="/A066909/b066909.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A066838(n) modulo n. - _Michel Marcus_, May 20 2014

%F a(prime(n)) = A062347(n-1). - _Michel Marcus_, May 20 2014

%e a(8) = (3 * 5 * 7) (mod 8) = 1 because 3, 5 and 7 are the primes < 8 that do not divide 8.

%o (PARI) a(n) = prod(i=1, n-1, if (isprime(i) && (n%i) , i, 1)) % n; \\ _Michel Marcus_, May 20 2014

%Y Cf. A062347, A066838.

%K nonn,easy

%O 1,3

%A _Leroy Quet_, Jan 22 2002