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A066369 Number of subsets of {1, ..., n} with no four terms in arithmetic progression. +0
1
1, 2, 4, 8, 15, 29, 56, 103, 192, 364, 668, 1222, 2233, 3987, 7138, 12903, 22601, 40200, 71583, 125184, 218693, 386543, 670989, 1164385, 2021678, 3462265, 5930954, 10189081, 17266616, 29654738, 50912618 (list; graph; listen)
OFFSET

0,2

EXAMPLE

a(5) = 29 because there are 32 subsets and three of them contain four terms in arithmetic progression: {1, 2, 3, 4}, {2, 3, 4, 5} and {1, 2, 3, 4, 5}.

CROSSREFS

Cf. A051013.

Adjacent sequences: A066366 A066367 A066368 this_sequence A066370 A066371 A066372

Sequence in context: A036621 A001383 A108564 this_sequence A000078 A034338 A166861

KEYWORD

nonn

AUTHOR

Jan Kristian Haugland (jankrihau(AT)hotmail.com), Dec 22 2001

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Last modified November 9 12:23 EST 2009. Contains 166233 sequences.


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