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

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

Author

Rémy Sigrist, May 01 2018

Keywords

• nonn
• easy
• mult

Comments

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

This sequence is a variant of A303809.

Links

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

Crossrefs

Cf. A002110, A014222, A303809, A303823.

Programs

PARI

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

Formula

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.