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A092482
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Sequence contains no 3-term arithmetic progression, starting with "illegal" 1,2,3.
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7
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1, 2, 3, 6, 7, 14, 15, 17, 18, 36, 37, 39, 40, 45, 46, 48, 49, 98, 99, 101, 102, 107, 108, 110, 111, 125, 126, 128, 129, 134, 135, 137, 138, 276, 277, 279, 280, 285, 286, 288, 289, 303, 304, 306, 307, 312, 313, 315, 316, 357, 358, 360, 361, 366, 367, 369, 370
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(1)=1, a(2)=2, a(3)=3; a(n) is least k such that no three terms of a(1), a(2), ..., a(n-1), k form an arithmetic progression, except for the first triple (1,2,3).
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LINKS
| Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
| For n>2, a(n+2) = 1 + 2^[log2(n)] + sum[k=1, n, (3^A007814(n)+1)/2] = 1 + A053644(n) + A005836(n) (conjectured and checked up to n=512).
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CROSSREFS
| Cf. A004793, A033157.
Sequence in context: A182708 A183558 A172105 * A147303 A075427 A066880
Adjacent sequences: A092479 A092480 A092481 * A092483 A092484 A092485
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KEYWORD
| nonn
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AUTHOR
| Ralf Stephan, Apr 04 2004
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