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A016185
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a(n) = 9^n - 8^n.
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18
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0, 1, 17, 217, 2465, 26281, 269297, 2685817, 26269505, 253202761, 2413042577, 22791125017, 213710059745, 1992110014441, 18478745943857, 170706760005817, 1571545212141185, 14425381885981321, 132080236787517137, 1206736529597136217, 11004743954450081825
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OFFSET
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0,3
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LINKS
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Table of n, a(n) for n=0..20.
John Elias, Illustration of initial terms: Sierpinski Carpet
Wikipedia, Sierpinski carpet
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FORMULA
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G.f.: x/((1-8x)(1-9x)).
E.g.f.: e^(9*x) - e^(8*x). - Mohammad K. Azarian, Jan 14 2009
a(n) = 9*a(n-1) + 8^(n-1), a(0)=0. - Vincenzo Librandi, Feb 09 2011
a(n) = 17*a(n-1) - 72*a(n-2), a(0)=0, a(1)=1. - Vincenzo Librandi, Feb 09 2011
a(n) = A001019(n) - A001018(n). - Alois P. Heinz, Aug 19 2021
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MATHEMATICA
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Join[{a=0, b=1}, Table[c=17*b-72*a; a=b; b=c, {n, 40}]] (* Vladimir Joseph Stephan Orlovsky, Feb 09 2011 *)
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CROSSREFS
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Cf. A001018, A001019.
Sequence in context: A009441 A016293 A139733 * A125452 A322538 A016238
Adjacent sequences: A016182 A016183 A016184 * A016186 A016187 A016188
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane
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STATUS
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approved
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