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A026476
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For n>3, a(n) = 7*n - 21 + 2*(-1)^n.
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3
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1, 3, 4, 9, 12, 23, 26, 37, 40, 51, 54, 65, 68, 79, 82, 93, 96, 107, 110, 121, 124, 135, 138, 149, 152, 163, 166, 177, 180, 191, 194, 205, 208, 219, 222, 233, 236, 247, 250, 261, 264, 275, 278, 289, 292, 303, 306, 317, 320, 331, 334, 345, 348, 359, 362, 373, 376
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OFFSET
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1,2
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COMMENTS
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The old definition of this sequence was "a(n) = least positive integer > a(n-1) and not equal to a(i)+a(j)+a(k) for 1<=i<=j<=k<=n". However, Ralf Stephan observes that this does not fit the terms shown. (It produces A109474.) The present definition (due to Stephan) has been adopted as a temporary solution. It would be nice to have a definition similar to the original one. - N. J. A. Sloane, Nov 24 2004
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LINKS
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Table of n, a(n) for n=1..57.
Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).
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FORMULA
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a(n) = a(n-1)+a(n-2)-a(n-3) for n>6. G.f.: x*(1+2*x+3*x^3+2*x^4+6*x^5)/((1-x)^2*(1+x)). [Colin Barker, May 02 2012]
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CROSSREFS
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Cf. A026472, A026474, A109474.
Sequence in context: A105137 A025613 A097063 * A002513 A034418 A034421
Adjacent sequences: A026473 A026474 A026475 * A026477 A026478 A026479
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KEYWORD
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nonn,easy
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AUTHOR
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Clark Kimberling
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EXTENSIONS
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More terms from David Duran (dduran(AT)ashland.edu), Dec 14 2005
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STATUS
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approved
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