A303809 -id:A303809 - cp's OEIS frontend

A303819 a(n) is the least k > 0 such that A303809(k) = 2^n.

1, 2, 4, 12, 16, 48, 144, 720, 1296, 6480, 32400, 184320, 331776, 1658880, 8294400, 58060800, 65536, 196608, 589824, 2949120, 5308416, 26542080, 132710400, 928972800, 3317760000, 23224320000, 162570240000, 1788272640000, 7965941760000, 87625359360000

Offset: 0

Rémy Sigrist, May 01 2018

nonn

All terms belongs to A025487.

Rémy Sigrist, Table of n, a(n) for n = 0..180
Rémy Sigrist, PARI program for A303819
Rémy Sigrist, Scatterplot of (n, k) such that n, k <= 286 and a(k) divides a(n)

Cf. A025487, A303809.

PARI
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A303822 Multiplicative with a(p^k) = 3^a(k).

Original entry on oeis.org

1, 3, 3, 27, 3, 9, 3, 27, 27, 9, 3, 81, 3, 9, 9, 7625597484987, 3, 81, 3, 81, 9, 9, 3, 81, 27, 9, 27, 81, 3, 27, 3, 27, 9, 9, 9, 729, 3, 9, 9, 81, 3, 27, 3, 81, 81, 9, 3, 22876792454961, 27, 81, 9, 81, 3, 81, 9, 81, 9, 9, 3, 243, 3, 9, 81, 19683, 9, 27, 3, 81

Offset: 1

Rémy Sigrist, May 01 2018

This sequence contains every power of 3; see A303823 for the corresponding least indices.

This sequence is a variant of A303809.

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Cf. A002110, A014222, A303809, A303823.

a(n) = my (f=factor(n)); prod (i=1, #f~, 3^a(f[i, 2]))

a(n) = n iff n = A014222(k) for some k > 0.
a(A002110(k)) = 3^k for any k >= 0.
a(n) = 3 iff n is prime.

cp's OEIS Frontend

A303819 a(n) is the least k > 0 such that A303809(k) = 2^n.

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