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A019677
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Expansion of 1/((1-4x)(1-8x)(1-12x)).
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4
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1, 24, 400, 5760, 77056, 989184, 12390400, 152862720, 1867841536, 22682271744, 274333696000, 3309180026880, 39847582498816, 479270434504704, 5760041038643200, 69190860134154240, 830853267268304896, 9974742789667160064, 119732942204305408000
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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) = (4^n)*Stirling2(n+3, 3), n >= 0, with Stirling2(n, m) = A008277(n, m).
a(n) = (4^n - 8*8^n + 9*12^n)/2.
G.f.: 1/((1-4*x)*(1-8*x)*(1-12*x)).
E.g.f.: (d^3/dx^3)((((exp(4*x)-1)/4)^3)/3!) = (exp(4*x) - 8*exp(8*x) + 9*exp(12*x))/2.
a(0)=1, a(1)=24, a(2)=400; for n > 2, a(n) = 24*a(n-1) - 176*a(n-2) + 384*a(n-3). - Vincenzo Librandi, Jul 03 2013
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MAPLE
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a:= n-> (Matrix(3, (i, j)-> `if`(i=j-1, 1, `if`(j=1, [24, -176, 384][i], 0)))^n)[1, 1]: seq(a(n), n=0..25); # Alois P. Heinz, Jul 03 2013
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MATHEMATICA
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CoefficientList[Series[1 / ((1 - 4 x) (1 - 8 x) (1 - 12 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 03 2013 *)
LinearRecurrence[{24, -176, 384}, {1, 24, 400}, 20] (* Harvey P. Dale, Jul 18 2020 *)
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PROG
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(Magma) m:=20; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/((1-4*x)*(1-8*x)*(1-12*x)))); /* or */ I:=[1, 24, 400]; [n le 3 select I[n] else 24*Self(n-1)-176*Self(n-2)+384*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Jul 03 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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