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A020606 Expansion of 1/((1-6x)(1-9x)(1-11x)). 1
1, 26, 457, 6782, 91693, 1170218, 14373409, 171896534, 2016642805, 23325176930, 266916367081, 3029497622606, 34167408893437, 383440973924762, 4286324362209073, 47766301010614598, 530982729463501189 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
a(0)=1, a(1)=26, a(2)=457, a(n)=26*a(n-1)-219*a(n-2)+594*a(n-3). [Harvey P. Dale, Oct 26 2011]
a(n) = (3*11^(n+2) - 5*9^(n+2) + 2*6^(n+2))/30. [Yahia Kahloune, Jun 30 2013]
a(n) = 20*a(n-1) -99*a(n-2) +6^n. - Vincenzo Librandi, Jul 04 2013
MATHEMATICA
CoefficientList[Series[1 / ((1 - 6 x) (1 - 9 x) (1 - 11 x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{26, -219, 594}, {1, 26, 457}, 20] (* Harvey P. Dale, Oct 26 2011 *)
PROG
(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-6*x)*(1-9*x)*(1-11*x)))); /* or */ I:=[1, 26, 457]; [n le 3 select I[n] else 26*Self(n-1)-219*Self(n-2)+594*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Jul 04 2013
CROSSREFS
Sequence in context: A020968 A025955 A022725 * A021984 A025954 A158436
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified June 15 09:26 EDT 2024. Contains 373407 sequences. (Running on oeis4.)