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A027261
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a(n) = Sum_{k=0..2n} (k+1) * A025177(n, k).
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5
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1, 4, 18, 72, 270, 972, 3402, 11664, 39366, 131220, 433026, 1417176, 4605822, 14880348, 47829690, 153055008, 487862838, 1549681956, 4907326194, 15496819560, 48814981614, 153418513644, 481176247338, 1506290861232, 4707158941350, 14686335897012, 45753584909922
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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) = 2(n+1)*3^(n-1), for n>1 (conjectured). - Ralf Stephan, Feb 02 2004
Conjecture: a(n) = 6*a(n-1)-9*a(n-2), for n>3.
G.f.: (1-9*x^2+18*x^3)/(1-3*x)^2. (End)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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