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A261399
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a(1)=1; thereafter a(n) = (2/5)*(9*6^(n-2)+1).
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1
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1, 4, 22, 130, 778, 4666, 27994, 167962, 1007770, 6046618, 36279706, 217678234, 1306069402, 7836416410, 47018498458, 282110990746, 1692665944474, 10155995666842, 60935974001050, 365615844006298, 2193695064037786, 13162170384226714, 78973022305360282, 473838133832161690
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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G.f.: x-2*x^2*(-2+3*x) / ( (6*x-1)*(x-1) ). - R. J. Mathar, Aug 19 2015
a(n) = 7*a(n-1) - 6*a(n-2), n > 2.
a(n) = 6*a(n-1) - 2, n > 1.
a(n) = 3*6^(n-2) + a(n-1), n > 1.
(End)
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CROSSREFS
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The number 22, the third term here, is the same 22 seen in A261400 and illustrated in a link in that entry.
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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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