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A133681
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a(n)=9*a(n-1)+90*a(n-2) for n>=3, a(0)=1, a(1)=9, a(2)=162 .
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1
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1, 9, 162, 2268, 34992, 519048, 7820712, 117100728, 1757770632, 26359001208, 395430367752, 5931183418488, 88969383864072, 1334530962440568, 20018023209731592, 300269995507235448, 4504052048440962312
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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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G.f.: (1-9*x^2)/(1-9*x-90*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*9^k .
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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