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A020567
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Expansion of 1/((1-5x)(1-10x)(1-11x)).
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1
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1, 26, 461, 6946, 95781, 1250466, 15739501, 193056386, 2323229621, 27553572706, 323079534141, 3753826047426, 43291842381061, 496209045488546, 5658293396858381, 64241196847864066, 726653012738614101
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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) = 5*5^n/6 -20*10^n +121*11^n/6. - R. J. Mathar, Jun 30 2013
a(0)=1, a(1)=26, a(2)=461; for n>2, a(n) = 26*a(n-1) -215*a(n-2) +550*a(n-3). - Vincenzo Librandi, Jul 04 2013
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MATHEMATICA
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CoefficientList[Series[1 / ((1 - 5 x) (1 - 10 x) (1 - 11 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 04 2013 *)
LinearRecurrence[{26, -215, 550}, {1, 26, 461}, 20] (* Harvey P. Dale, Aug 19 2020 *)
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PROG
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(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-5*x)*(1-10*x)*(1-11*x)))); /* or */ I:=[1, 26, 461]; [n le 3 select I[n] else 26*Self(n-1)-215*Self(n-2)+550*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Jul 04 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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