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A107378
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Expansion of x*(1-3*x-2*x^2)/(1-4*x+4*x^3+x^4).
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1
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0, 1, 1, 2, 4, 11, 35, 122, 440, 1609, 5913, 21770, 80204, 295555, 1089227, 4014322, 14794864, 54526993, 200961457, 740652050, 2729705364, 10060448635, 37078224883, 136653426026, 503642204200, 1856195468633, 6841089945545
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OFFSET
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0,4
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COMMENTS
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Sequence produced by 4 X 4 Markov chain with characteristic polynomial x^4-4*x^3+4*x+1.
Setting m=3 gives a Fibonacci sequence.
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LINKS
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MATHEMATICA
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m = 4 M = {{0, 1, 0, 0}, {0, 0, 1, 0}, {0, 0, 0, 1}, {-1, -m, 0, m}} Expand[Det[M - x*IdentityMatrix[4]]] NSolve[Det[M - x*IdentityMatrix[4]] == 0, x] v[1] = {0, 1, 1, 2}; v[n_] := v[n] = M.v[n - 1]; digits = 50; a = Table[v[n][[1]], {n, 1, digits}]
CoefficientList[Series[x (1-3x-2x^2)/(1-4x+4x^3+x^4), {x, 0, 30}], x] (* or *) LinearRecurrence[{4, 0, -4, -1}, {0, 1, 1, 2}, 30] (* Harvey P. Dale, Aug 30 2020 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,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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