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Search: id:A093679
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| A093679 |
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Sequence contains no 3-term arithmetic progression, starting with 1,10. |
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+0
3
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| 1, 10, 11, 13, 14, 20, 22, 23, 28, 37, 38, 40, 41, 47, 49, 50, 82, 91, 92, 94, 95, 101, 103, 104, 109, 118, 119, 121, 122, 128, 130, 131, 244, 253, 254, 256, 257, 263, 265, 266, 271, 280, 281, 283, 284, 290, 292, 293, 325, 334, 335, 337, 338, 344, 346, 347
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(1)=1, a(2)=10; a(n) is least k such that no three terms of a(1),a(2),...,a(n-1),k form an arithmetic progression.
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FORMULA
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a(n) = sum[k=1, n-1, (3^A007814(k)+1)/2] + f(n), with f(n) an 8-periodic function with values {1, 9, 8, 9, 5, 10, 10, 10, ...}, n>=1, as proved by Lawrence Sze.
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CROSSREFS
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Cf. A004793, A033157, A093678-A093681, A092482.
Row 4 of array in A093682.
Adjacent sequences: A093676 A093677 A093678 this_sequence A093680 A093681 A093682
Sequence in context: A077677 A107741 A047791 this_sequence A106439 A121263 A121295
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KEYWORD
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nonn
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AUTHOR
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Ralf Stephan (ralf(AT)ark.in-berlin.de), Apr 09 2004
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