A330681 a(n) = A283980(A025487(n)).

1, 6, 36, 30, 216, 180, 1296, 1080, 210, 7776, 900, 6480, 1260, 46656, 5400, 38880, 7560, 279936, 32400, 6300, 233280, 2310, 27000, 45360, 1679616, 194400, 37800, 1399680, 13860, 162000, 272160, 10077696, 1166400, 226800, 8398080, 83160, 972000, 44100, 1632960, 60466176, 189000, 6998400, 69300, 810000, 1360800

Offset: 1

Author

Antti Karttunen, Dec 26 2019

Keywords

• nonn

Comments

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.

Examples

			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.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..15703

Crossrefs

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

Programs

PARI

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
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.
v025487 = A025487list(64);
A025487(n) = v025487[n];
A330681(n) = A283980(A025487(n));

Formula

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

A046523(a(n)) = a(n).

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