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a(n) is the product of the distinct prime numbers appearing in the prime tower factorization of n.
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%I #12 Aug 13 2020 10:11:38

%S 1,2,3,2,5,6,7,6,6,10,11,6,13,14,15,2,17,6,19,10,21,22,23,6,10,26,3,

%T 14,29,30,31,10,33,34,35,6,37,38,39,30,41,42,43,22,30,46,47,6,14,10,

%U 51,26,53,6,55,42,57,58,59,30,61,62,42,6,65,66,67,34,69,70

%N a(n) is the product of the distinct prime numbers appearing in the prime tower factorization of n.

%C The prime tower factorization of a number is defined in A182318.

%C For any n > 0, a(n) is the product of the terms in n-th row of A336964.

%H Rémy Sigrist, <a href="/A336965/b336965.txt">Table of n, a(n) for n = 1..10000</a>

%e A001221(a(n)) = A115588(n) for any n > 1.

%e a(n) = A007947(A279513(n)).

%e a(n) = n iff n is squarefree (A005117).

%o (PARI) a(n) = { my (f=factor(n), v=vecprod(f[,1]~)); for (k=1, #f~, v=lcm(v, a(f[k,2]))); v }

%Y Cf. A001221, A005117, A007947, A115588, A182318, A336964.

%K nonn

%O 1,2

%A _Rémy Sigrist_, Aug 09 2020