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

1,2

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.

Links

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

Formula

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

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

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

Example

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.

Prog

(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));

Crossrefs

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

Sequence in context: A360442 A137868 A070401 * A070400 A222929 A222784

Adjacent sequences: A330678 A330679 A330680 * A330682 A330683 A330684

Keyword

nonn

Author

Antti Karttunen, Dec 26 2019

Status

approved