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A021284
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Expansion of 1/((1-x)(1-2x)(1-9x)(1-10x)).
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1
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1, 22, 335, 4400, 53481, 620202, 6970675, 76624900, 828512861, 8845504382, 93498427815, 980374738200, 10212261530641, 105799242660562, 1091082072825755, 11208627544304300, 114766536787594821
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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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a(n) = (7*10^(n+3) - 9^(n+4) + 9*2^(n+3) - 7)/504. - Yahia Kahloune, Jul 08 2013
a(0)=1, a(1)=22, a(2)=335, a(3)=4400; for n>3, a(n) = 22*a(n-1) -149*a(n-2) +308*a(n-3) -180*a(n-4). - Vincenzo Librandi, Jul 08 2013
a(0)=1, a(1)=22; for n>1 a(n) = 19*a(n-1) -90*a(n-2) +2^n -1. - Vincenzo Librandi, Jul 08 2013
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MATHEMATICA
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CoefficientList[Series[1 / ((1 - x) (1 - 2 x) (1 - 9 x) (1 - 10 x)), {x, 0, 20}], x] (* Vincenzo Librandi Jul 08 2013 *)
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PROG
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(Magma) I:=[1, 22, 335, 4400]; [n le 4 select I[n] else 22*Self(n-1)-149*Self(n-2)+308*Self(n-3)-180*Self(n-4): n in [1..25]]; /* or */ m:=25; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-x)*(1-2*x)*(1-9*x)*(1-10*x)))); // Vincenzo Librandi, Jul 08 2013
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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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