A094708 Size of the smallest set hitting all {x, 2x, 3x} contained in D(n) = the first n 3-smooth numbers {1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 27,...} (A003586).

0, 0, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 9, 9, 10, 10, 11, 11, 11, 11, 12, 12, 13, 13, 13, 13, 13, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 21

Offset: 1

Author

Barry Cipra, Jun 15 2004

Keywords

• nonn

Comments

A057561(n) = n - a(n). [Steven Finch, Feb 25 2009]

Links

• F. Chung, P. Erdős and R. L. Graham, On Sparse Sets Hitting Linear Forms, in Number Theory for the Millennium I (M. A. Bennett et al., eds.), 2002, pp. 257-272.
• Steven R. Finch, Triple-Free Sets of Integers [From Steven Finch, Apr 20 2019]

Crossrefs

Cf. A003586, A057561.

Extensions

More terms from Sean A. Irvine, Nov 19 2015