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A131290
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1 followed by period 6: repeat [3, 2, 0, -1, 0, 2].
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2
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1, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1, 0, 2, 3, 2, 0, -1
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: (1+x-2*x^2+x^3)/((1-x)*(1-x+x^2)). - R. J. Mathar, Feb 27 2008
If n mod 6 = 4 then a(n) = (Fibonacci(n-3)*Fibonacci(n+1)) mod 4 -2, else a(n) = (Fibonacci(n-3)*Fibonacci(n+1)) mod 4, n>0. - Gary Detlefs, Dec 12 2010
a(n) = 2*a(n-1) - 2*a(n-2) + a(n-3) for n>4.
a(0) = 1, a(n) = 1 + cos(n*Pi/3) + sqrt(3)*sin(n*Pi/3) for n>0. (End)
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MAPLE
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A131290 := proc(n) if n = 0 then 1; else op(((n-1)mod 6)+1, [3, 2, 0, -1, 0, 2]) ; fi ; end: seq(A131290(n), n=0..100) ; # R. J. Mathar, Feb 27 2008
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MATHEMATICA
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PadRight[{1}, 110, {2, 3, 2, 0, -1, 0}] (* or *) Join[{1}, LinearRecurrence[ {2, -2, 1}, {3, 2, 0}, 110]] (* Harvey P. Dale, Jun 22 2012 *)
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PROG
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(Magma) [1] cat &cat [[3, 2, 0, -1, 0, 2]^^30]; // Wesley Ivan Hurt, Jun 20 2016
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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