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A106805 G.f.: 1 / (1-2*x-x^2+x^3). 0

%I

%S 1,2,5,11,25,56,126,283,636,1429,3211,7215,16212,36428,81853,183922,

%T 413269,928607,2086561,4688460,10534874,23671647,53189708,119516189,

%U 268550439,603427359,1355888968,3046654856,6845771321,15382308530,34563733525,77664004259

%N G.f.: 1 / (1-2*x-x^2+x^3).

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2, 1, -1).

%F G.f. for sequence with 1 prepended: 1/( 1 - sum(k>=0, x*(x+x^2-x^3)^k ) ). [_Joerg Arndt_, Sep 30 2012]

%t 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}]

%t LinearRecurrence[{2, 1, -1}, {1, 2, 5}, 60] (* _Vladimir Joseph Stephan Orlovsky_, Feb 13 2012 *)

%o (PARI) Vec( 1 / (1-2*x-x^2+x^3) + O(x^66) ) /* _Joerg Arndt_, Sep 30 2012 */

%Y A006054 shifted left twice.

%K nonn

%O 0,2

%A _Roger L. Bagula_, May 17 2005

%E Edited by the Associate Editors of the OEIS, Apr 09 2009

%E Name corrected, _Joerg Arndt_, Sep 30 2012.

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Last modified June 23 04:15 EDT 2021. Contains 345395 sequences. (Running on oeis4.)