A327469 Number of nonempty subsets of [1..n] which are geometric progressions of length >= 3 with rational ratio and are locally maximal.

0, 0, 0, 1, 1, 1, 1, 1, 3, 3, 3, 4, 4, 4, 4, 5, 5, 7, 7, 8, 8, 8, 8, 8, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 19, 19, 19, 19, 19, 19, 19, 19, 20, 22, 22, 22, 23, 29, 33, 33, 34, 34, 34, 34, 34, 34, 34, 34, 35, 35, 35, 37, 40, 40, 40, 40, 41, 41, 41, 41, 45, 45, 45, 49, 50, 50, 50, 50, 51, 55, 55, 55, 56, 56, 56, 56, 56, 56, 58, 58, 59, 59, 59, 59, 60, 60, 66, 68, 77

Offset: 1

Author

N. J. A. Sloane, Oct 03 2019, using data computed by Rob Pratt

Keywords

• nonn

Comments

Exceptionally, DATA section give first 100 terms.

One might have expected that the GP would be required to have an integer ratio, but in fact we allow rational ratios. The GPs can be assumed to be increasing.

Crossrefs

Cf. A309095, A327466.