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a(n) = A283980(A025487(n)).
3

%I #13 Dec 26 2019 15:43:58

%S 1,6,36,30,216,180,1296,1080,210,7776,900,6480,1260,46656,5400,38880,

%T 7560,279936,32400,6300,233280,2310,27000,45360,1679616,194400,37800,

%U 1399680,13860,162000,272160,10077696,1166400,226800,8398080,83160,972000,44100,1632960,60466176,189000,6998400,69300,810000,1360800

%N a(n) = A283980(A025487(n)).

%C After 1, contains only the least representatives of such prime signatures where the maximal exponent occurs more than once. However, here the terms are not in ascending order.

%H Antti Karttunen, <a href="/A330681/b330681.txt">Table of n, a(n) for n = 1..15703</a>

%F a(n) = A283980(A025487(n)).

%F A046523(a(n)) = a(n).

%F A085089(a(n)) = A101296(a(n)) = A330683(n).

%e For example, 180 = 2^2 * 3^2 * 5^1 is present, because the maximal exponent in its prime factorization is 2, which occurs as an exponent of both 2 and 3, and because 180 is the minimal representative of the prime signature (2,2,1), as A046523(180) = 180.

%o (PARI)

%o A283980(n) = {my(f=factor(n)); prod(i=1, #f~, my(p=f[i, 1], e=f[i, 2]); if(p==2, 6, nextprime(p+1))^e)}; \\ From A283980

%o A025487list(e) = { my(lista = List([1, 2]), i=2, u = 2^e, t); while(lista[i] != u, if(2*lista[i] <= u, listput(lista,2*lista[i]); t = A283980(lista[i]); if(t <= u, listput(lista,t))); i++); vecsort(Vec(lista)); }; \\ Returns a list of terms up to the term 2^e.

%o v025487 = A025487list(64);

%o A025487(n) = v025487[n];

%o A330681(n) = A283980(A025487(n));

%Y Cf. A025487, A046523, A283980, A329899, A330683.

%K nonn

%O 1,2

%A _Antti Karttunen_, Dec 26 2019