id:A088808 - OEIS Search Results

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Number of subsets of {1, ..., n} that are not double-free.

+0
6

0, 0, 1, 2, 6, 12, 34, 68, 160, 320, 736, 1472, 3136, 6272, 13504, 27008, 56176, 112352, 234064, 468128, 954976, 1909952, 3913504, 7827008, 15878656, 31757312, 64413184, 128826368, 259449856, 518899712, 1046785024, 2093570048 (list; graph; listen)

	OFFSET	`0,4`
	COMMENT	`a(n) = 2^n - A050291(n); a(2k+1) = a(2k)2;` `a non double-free subset contains at least one subset {x,y} with y=2x.`
	LINKS	`T. D. Noe, Table of n, a(n) for n=0..400` `S. R. Finch, Triple-Free Sets of Integers` `Eric Weisstein's World of Mathematics, Double-Free Set` `Reinhard Zumkeller, Illustration of initial terms`
	CROSSREFS	`Cf. A000079.` `Sequence in context: A057579 A096610 A164099 this_sequence A076278 A099576 A026549` `Adjacent sequences: A088805 A088806 A088807 this_sequence A088809 A088810 A088811`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 19 2003`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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