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A136249
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a(n)=-a(n-1)+4*a(n-2)+4*a(n-3).
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1
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4, -2, 1, 7, -11, 43, -59, 187, -251, 763, -1019, 3067, -4091, 12283, -16379, 49147, -65531, 196603, -262139, 786427, -1048571, 3145723, -4194299, 12582907, -16777211, 50331643, -67108859, 201326587, -268435451, 805306363, -1073741819, 3221225467
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OFFSET
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0,1
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LINKS
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FORMULA
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a(2*n)=5-2^(2*n), a(2*n+1)=10-3*a(2n).
a(n) = 1/6*2^n*a(0) + 1/4*2^n*a(1) - 1/2*a(0)*(-2)^n - 1/3*(-1)^n*a(2) - 1/4*a(1)*(-2)^n + 4/3*(-1)^n*a(0) + 1/4*(-2)^n*a(2) + 1/12*2^n*a(2). - Alexander R. Povolotsky, Mar 31 2008
G.f.: (4+2*x-17*x^2)/((1+2*x)*(1-2*x)*(1+x)). a(n)=2^(n-2)+5*(-1)^n*(1-2^(n-2)). - R. J. Mathar, Jun 15 2009
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MATHEMATICA
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LinearRecurrence[{-1, 4, 4}, {4, -2, 1}, 50] (* or *) Table[(5(-2)^n- 40(-1)^n+2^n)/8, {n, 50}] (* Harvey P. Dale, Jun 10 2011 *)
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PROG
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(Magma) [2^(n-2)+5*(-1)^n*(1-2^(n-2)): n in [0..40]]; // Vincenzo Librandi, Aug 09 2011
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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