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 A178646 a(n) = product of divisors d of n such that d^k is not equal to n for any k >= 1. 1

%I

%S 1,1,1,1,1,6,1,4,1,10,1,144,1,14,15,8,1,324,1,400,21,22,1,13824,1,26,

%T 9,784,1,27000,1,512,33,34,35,46656,1,38,39,64000,1,74088,1,1936,2025,

%U 46,1,5308416,1,2500

%N a(n) = product of divisors d of n such that d^k is not equal to n for any k >= 1.

%F a(n) = A007955(n) / A157068 (n).

%F a(1) = 1, a(p) = 1, a(pq) = 1, a(pq...z) = (pq…z)^2((k-1)-1), for p, q = primes, k = natural numbers, pq...z = product of k (k > 2) distinct primes p, q, ..., z.

%e For n = 16, set of such divisors is {1, 8}; a(16) = 1*8=8.

%o (Sage) A178646 = lambda n: prod(d for d in divisors(n) if not n.is_power_of(d)) # [D. S. McNeil, Dec 28 2010]

%K nonn

%O 1,6

%A _Jaroslav Krizek_, Dec 25 2010

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Last modified September 19 03:31 EDT 2021. Contains 347550 sequences. (Running on oeis4.)