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A074986 Number of nonempty subsets of {1,2,3,...,n} that are closed under both GCD and LCM. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..57.

CROSSREFS

Cf. A051839, A122977, A122978.

Sequence in context: A270836 A100456 A059819 * A307435 A123328 A226175

Adjacent sequences:  A074983 A074984 A074985 * A074987 A074988 A074989

KEYWORD

nonn

AUTHOR

John W. Layman, Oct 02 2002

EXTENSIONS

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

STATUS

approved

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Last modified June 24 12:30 EDT 2021. Contains 345416 sequences. (Running on oeis4.)