This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A066909 #21 May 11 2024 16:18:39 %S A066909 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 A066909 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 A066909 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 A066909 (product of primes < n that do not divide n) (mod n). %H A066909 John Tyler Rascoe, <a href="/A066909/b066909.txt">Table of n, a(n) for n = 1..10000</a> %F A066909 a(n) = A066838(n) modulo n. - _Michel Marcus_, May 20 2014 %F A066909 a(prime(n)) = A062347(n-1). - _Michel Marcus_, May 20 2014 %e A066909 a(8) = (3 * 5 * 7) (mod 8) = 1 because 3, 5 and 7 are the primes < 8 that do not divide 8. %o A066909 (PARI) a(n) = prod(i=1, n-1, if (isprime(i) && (n%i) , i, 1)) % n; \\ _Michel Marcus_, May 20 2014 %Y A066909 Cf. A062347, A066838. %K A066909 nonn,easy %O A066909 1,3 %A A066909 _Leroy Quet_, Jan 22 2002