A284698 Numbers k such that A284695(k) <= 3.

1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 27, 36, 48, 54, 64, 72, 81, 108, 144, 162, 192, 216, 256, 324, 432, 512, 576, 648, 729, 768, 1296, 1458, 1536, 1728, 2304, 2916, 4096, 4608, 5184, 5832, 6561, 6912, 11664, 12288, 13122, 13824, 19683, 20736, 26244, 36864

Offset: 1

Author

Rémy Sigrist, Apr 01 2017

Keywords

• nonn

Comments

This sequence is a subsequence of the 3-smooth numbers (A003586).

This sequence could be interpreted as the "recursive" 3-smooth numbers.

If i and j belong to this sequence, then 2^i, 3^j and 2^i*3^j also belong to this sequence.

This sequence contains the nonzero values in A014221 and in A014222.

Examples

			1762613844998129336721604608 = 2^3^(2^2) * 3^(2*3) appears in this sequence.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..1331 (terms up to 10^1000)
• Rémy Sigrist, PARI program for A284698
• Rémy Sigrist, Logarithmic scatterplot of the terms up to 10^10000

Crossrefs

Cf. A003586, A014221, A014222, A284695.