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A060352
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a(n) = n*3^n - 1.
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7
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2, 17, 80, 323, 1214, 4373, 15308, 52487, 177146, 590489, 1948616, 6377291, 20726198, 66961565, 215233604, 688747535, 2195382770, 6973568801, 22082967872, 69735688019, 219667417262, 690383311397, 2165293113020
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OFFSET
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1,1
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LINKS
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FORMULA
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G.f.: x*(2-3*x)*(1+3*x)/((1-x)*(1-3*x)^2). - Colin Barker, Apr 22 2012
a(n) = 7*a(n-1) - 15*a(n-2) + 9*a(n-3), a(1)=2, a(2)=17, a(3)=80. - Harvey P. Dale, Dec 14 2012
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MATHEMATICA
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LinearRecurrence[{7, -15, 9}, {2, 17, 80}, 50] (* Harvey P. Dale, Dec 14 2012 *)
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PROG
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(PARI) { for (n=1, 200, write("b060352.txt", n, " ", n*3^n - 1); ) } \\ Harry J. Smith, Jul 04 2009
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CROSSREFS
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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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