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A106805
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G.f.: 1 / (1-2*x-x^2+x^3).
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0
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1, 2, 5, 11, 25, 56, 126, 283, 636, 1429, 3211, 7215, 16212, 36428, 81853, 183922, 413269, 928607, 2086561, 4688460, 10534874, 23671647, 53189708, 119516189, 268550439, 603427359, 1355888968, 3046654856, 6845771321, 15382308530, 34563733525, 77664004259
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..31.
Index entries for linear recurrences with constant coefficients, signature (2, 1, -1).
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FORMULA
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G.f. for sequence with 1 prepended: 1/( 1 - sum(k>=0, x*(x+x^2-x^3)^k ) ). [Joerg Arndt, Sep 30 2012]
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MATHEMATICA
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M = {{0, 0, 1}, {1, 2, 0}, {1, 1, 0}}; Det[M - x*IdentityMatrix[3]] v[0] = {0, 1, 1} v[n_]: = v[n]=M.v[n - 1] a = Table[v[n][[2]], {n, 0, 50}]
LinearRecurrence[{2, 1, -1}, {1, 2, 5}, 60] (* Vladimir Joseph Stephan Orlovsky, Feb 13 2012 *)
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PROG
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(PARI) Vec( 1 / (1-2*x-x^2+x^3) + O(x^66) ) /* Joerg Arndt, Sep 30 2012 */
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CROSSREFS
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A006054 shifted left twice.
Sequence in context: A017920 A228765 A006054 * A094981 A304969 A239812
Adjacent sequences: A106802 A106803 A106804 * A106806 A106807 A106808
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KEYWORD
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nonn
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AUTHOR
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Roger L. Bagula, May 17 2005
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EXTENSIONS
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Edited by the Associate Editors of the OEIS, Apr 09 2009
Name corrected, Joerg Arndt, Sep 30 2012.
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STATUS
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approved
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