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A038372 Largest subset of integers [ 1...n ] such that no member divides two others. 0
1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 8, 8, 9, 10, 10, 11, 12, 12, 13, 14, 14, 15, 16, 16, 17, 18, 19, 20, 21, 21, 22, 22, 22, 23, 24, 24, 25, 26, 26, 27, 28, 28, 29, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

R. K. Guy, Unsolved Problems Number Theory, B24.

LINKS

Table of n, a(n) for n=1..44.

FORMULA

a(n) >= ceiling(2n/3). For large n, 0.6725n <= a(n) <= 0.6736n (see Guy).

EXAMPLE

{6,8-17,19-23,25-29} is the largest set of positive integers <= 29 such that none of them divides two of the others. The cardinality of the set is 21, so a(29)=21.

CROSSREFS

Sequence in context: A032509 A322042 A004523 * A121930 A020909 A075357

Adjacent sequences:  A038369 A038370 A038371 * A038373 A038374 A038375

KEYWORD

nonn

AUTHOR

John W. Layman

EXTENSIONS

More terms and additional comments from Jud McCranie, Jan 17 2001

STATUS

approved

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Last modified August 3 04:47 EDT 2021. Contains 346435 sequences. (Running on oeis4.)