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Product_{h|n and h mod 6 = 1} h; product of divisors of n of the form 6*k + 1.
6

%I #24 Jul 10 2017 06:02:22

%S 1,1,1,1,1,1,7,1,1,1,1,1,13,7,1,1,1,1,19,1,7,1,1,1,25,13,1,7,1,1,31,1,

%T 1,1,7,1,37,19,13,1,1,7,43,1,1,1,1,1,343,25,1,13,1,1,55,7,19,1,1,1,61,

%U 31,7,1,13,1,67,1,1,7,1,1,73,37,25,19,7,13,79,1,1,1,1,7,85,43,1,1,1,1,8281

%N Product_{h|n and h mod 6 = 1} h; product of divisors of n of the form 6*k + 1.

%H Antti Karttunen, <a href="/A140213/b140213.txt">Table of n, a(n) for n = 1..10001</a>

%p A140213 := proc(n)

%p a := 1;

%p for d in numtheory[divisors](n) do

%p if modp(d,6) = 1 then

%p a := a*d ;

%p end if;

%p end do:

%p a;

%p end proc: # _R. J. Mathar_, Dec 15 2015

%o (PARI) A140213(n) = { my(m=1); fordiv(n, d, if(1==(d%6), m *= d)); (m); }; \\ _Antti Karttunen_, Jul 09 2017

%Y Cf. A170824, A248909, A279060.

%K nonn,easy,look

%O 1,7

%A _R. J. Mathar_, Jun 27 2008

%E More terms from _D. S. McNeil_, Mar 24 2009