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A166249
a(n) = 2*a(n-1) - a(n-3) + 2*a(n-4) for n>3, a(0)=a(1)=1, a(2)=0, a(3)=2.
2
1, 1, 0, 2, 5, 12, 22, 43, 84, 170, 341, 684, 1366, 2731, 5460, 10922, 21845, 43692, 87382, 174763, 349524, 699050, 1398101, 2796204, 5592406, 11184811, 22369620, 44739242, 89478485, 178956972, 357913942, 715827883, 1431655764, 2863311530
OFFSET
0,4
FORMULA
From R. J. Mathar, Nov 09 2009: (Start)
G.f.: (1-x+3*x^3-2*x^2)/((1-2*x)*(1+x)*(x^2-x+1)).
a(n) = A001045(n) + A010892(n+1). (End)
MATHEMATICA
LinearRecurrence[{2, 0, -1, 2}, {1, 1, 0, 2}, 100] (* G. C. Greubel, May 08 2016 *)
CROSSREFS
Sequence in context: A215183 A086734 A123647 * A326762 A116711 A247658
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Oct 10 2009
EXTENSIONS
Edited by N. J. A. Sloane, Oct 13 2009
Extended by R. J. Mathar, Nov 09 2009
STATUS
approved