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A201865
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Expansion of 1/((1-3*x)*(1+7*x)).
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1
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1, -4, 37, -232, 1705, -11692, 82573, -575824, 4037329, -28241620, 197750389, -1384075576, 9689060473, -67821828988, 474757585885, -3323288752288, 23263064312737, -162841321048996, 1139889634763461, -7979226281082760, 55854587454363721, -390982101720192844
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OFFSET
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0,2
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LINKS
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Bruno Berselli, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-4,21).
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FORMULA
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G.f.: 1/((1-3*x)*(1+7*x)).
a(n) = (3^(n+1)+7*(-7)^n)/10.
a(n) = -4*a(n-1)+21*a(n-2) with n>0, a(-1)=0, a(0)=1.
a(n)-a(n-1) = A083300(n)*(-1)^n.
a(n)+5*a(n-1) = A083296(n) with a(-1)=0.
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MATHEMATICA
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CoefficientList[Series[1/((1-3*x)*(1+7*x)), {x, 0, 22}], x]
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PROG
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(PARI) Vec(1/((1-3*x)*(1+7*x))+O(x^22))
(Magma) m:=22; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-3*x)*(1+7*x))));
(Maxima) makelist(coeff(taylor(1/((1-3*x)*(1+7*x)), x, 0, n), x, n), n, 0, 21);
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CROSSREFS
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Cf. A014986, A083296, A083300.
Sequence in context: A063418 A095819 A335773 * A025542 A162649 A221059
Adjacent sequences: A201862 A201863 A201864 * A201866 A201867 A201868
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KEYWORD
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sign,easy
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AUTHOR
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Bruno Berselli, Dec 07 2011
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STATUS
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approved
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