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Search: id:A101399
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| A101399 |
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a(0) = 1, a(1) = 2, a(2) = 5; for n >= 3, a(n) = a(n - 1) + 2*a(n - 2) + a(n - 3) |
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+0
6
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| 1, 2, 5, 10, 22, 47, 101, 217, 466, 1001, 2150, 4618, 9919, 21305, 45761, 98290, 211117, 453458, 973982, 2092015, 4493437, 9651449, 20730338, 44526673, 95638798, 205422482, 441226751, 947710513, 2035586497, 4372234274
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Lengths of successive words (starting with a) under the substitution: {a -> ab, b -> aac, c -> a}.
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MATHEMATICA
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a[0] = 1; a[1] = 2; a[2] = 5; a[n_] := a[n] = a[n - 1] + 2a[n - 2] + a[n - 3]; Table[ a[n], {n, 0, 30}] (from Robert G. Wilson v Jan 15 2005)
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CROSSREFS
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Pairwise sums of A078007. Bisection of A003410 and A058278.
Sequence in context: A018004 A124329 A144520 this_sequence A018109 A123491 A166300
Adjacent sequences: A101396 A101397 A101398 this_sequence A101400 A101401 A101402
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KEYWORD
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nonn,easy
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AUTHOR
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J. F. J. Laros (jlaros(AT)liacs.nl), Jan 15 2005
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Lior Manor (lior.manor(AT)gmail.com) Jan 15 2005
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