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A016191
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Expansion of 1/((1-9x)(1-12x)).
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2
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1, 21, 333, 4725, 63261, 818181, 10349613, 128978325, 1590786621, 19476859941, 237209103693, 2877890303925, 34817113183581, 420347224031301, 5067043480830573, 61010412902061525, 733977975013590141
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Harvey P. Dale, Table of n, a(n) for n = 0..900
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FORMULA
| (12^(n+1)-9^(n+1))/3 - Lambert Klasen (lambert.klasen(AT)gmx.net), Feb 05 2005
a(n-1)=Sum(3^(n-1)*3^(n-k)*binomial(n, k),k=1..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 24 2006
a(0)=1, a(n)=12*a(n-1)+9^n. [From Vincenzo Librandi, Feb 09 2011]
a(0)=1, a(1)=21, a(n)=21*a(n-1)-108*a(n-2). [From Vincenzo Librandi, Feb 09 2011]
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MATHEMATICA
| CoefficientList[Series[1/((1-9x)(1-12x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{21, -108}, {1, 21}, 30] (* From Harvey P. Dale, Oct 15 2011 *)
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CROSSREFS
| Sequence in context: A011810 A091947 A016195 * A095905 A051525 A107396
Adjacent sequences: A016188 A016189 A016190 * A016192 A016193 A016194
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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