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A020571
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Expansion of 1/((1-6x)(1-7x)(1-9x)).
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1
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1, 22, 325, 4030, 45301, 478702, 4851925, 47752510, 460048501, 4362445582, 40876539925, 379553364190, 3499808594101, 32098136255662, 293160602826325, 2668857246099070, 24235419069434101, 219645625266148942
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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) = 12*6^n -49*7^n/2 +27*9^n/2. - R. J. Mathar, Jun 30 2013
a(0)=1, a(1)=22, a(2)=325; for n>2, a(n) = 22*a(n-1) -159*a(n-2) +378*a(n-3). - Vincenzo Librandi, Jul 04 2013
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MATHEMATICA
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CoefficientList[Series[1 / ((1 - 6 x) (1 - 7 x) (1 - 9 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 04 2013 *)
LinearRecurrence[{22, -159, 378}, {1, 22, 325}, 30] (* Harvey P. Dale, Dec 11 2018 *)
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PROG
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(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-6*x)*(1-7*x)*(1-9*x)))); /* or */ I:=[1, 22, 325]; [n le 3 select I[n] else 22*Self(n-1)-159*Self(n-2)+378*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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