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A066369
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Number of subsets of {1, ..., n} with no four terms in arithmetic progression.
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0
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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; refs; listen; history; internal format)
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OFFSET
| 0,2
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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}.
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CROSSREFS
| Cf. A051013.
Sequence in context: A036621 A001383 A108564 * A000078 A176503 A034338
Adjacent sequences: A066366 A066367 A066368 * A066370 A066371 A066372
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KEYWORD
| nonn
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AUTHOR
| Jan Kristian Haugland (jankrihau(AT)hotmail.com), Dec 22 2001
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