A074986 Number of nonempty subsets of {1,2,3,...,n} that are closed under both GCD and LCM.

1, 3, 5, 9, 11, 18, 20, 28, 32, 39, 41, 62, 64, 71, 78, 94, 96, 117, 119, 140, 147, 154, 156, 214, 218, 225, 233, 254, 256, 301, 303, 335, 342, 349, 356, 440, 442, 449, 456, 514, 516, 561, 563, 584, 605, 612, 614, 766, 770, 791, 798, 819, 821, 879, 886, 944, 951

Offset: 1

Author

John W. Layman, Oct 02 2002

Keywords

• nonn

Comments

I.e. number of division lattices with values from 1 to n. - Franklin T. Adams-Watters, Sep 21 2006

Links

• Sean A. Irvine, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A051839, A122977, A122978.

Extensions

More terms from Franklin T. Adams-Watters, Sep 21 2006