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0, 1, 4, 18, 84, 387, 1784, 8228, 37944, 174981, 806940, 3721270, 17160940, 79139079, 364956336, 1683025992, 7761412016, 35792386313, 165059516916, 761185462362, 3510269016516, 16187892672139, 74651791054120, 344262840164460, 1587596244438120
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: x/(1 - 4 x - 2 x^2 - 4 x^3 + x^4).
a(n) = 4*a(n-1) + 2*a(n-2) + 4*a(n-3) - a(n-4).
a(n) = (1/8)*A290915(n) for n >= 0.
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MATHEMATICA
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z = 60; s = x/(1 - x)^2; p = 1 - 8 s^2;
Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000027 *)
u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A290915 *)
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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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STATUS
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approved
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