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A168331
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a(n) = (5 + 14*n + 7*(-1)^n)/4.
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3
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3, 10, 10, 17, 17, 24, 24, 31, 31, 38, 38, 45, 45, 52, 52, 59, 59, 66, 66, 73, 73, 80, 80, 87, 87, 94, 94, 101, 101, 108, 108, 115, 115, 122, 122, 129, 129, 136, 136, 143, 143, 150, 150, 157, 157, 164, 164, 171, 171, 178, 178, 185, 185, 192, 192, 199, 199, 206, 206
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = 7*n - a(n-1) - 1, with n > 1, a(1)=3.
G.f.: x*(3+7*x-3*x^2) / ((1+x)*(x-1)^2). - R. J. Mathar, Jan 05 2011
a(1)=3, a(2)=10, a(3)=10; for n>3, a(n) = a(n-1)+a(n-2)-a(n-3). - Harvey P. Dale, Oct 24 2011
E.g.f.: (1/4)*(7 - 12*exp(x) + (5 + 14*x)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 18 2016
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MAPLE
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MATHEMATICA
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Table[5/4 + 7n/2 + 7 (-1)^n/4, {n, 60}] (* or *) LinearRecurrence[{1, 1, -1}, {3, 10, 10}, 60] (* Harvey P. Dale, Oct 24 2011 *)
CoefficientList[Series[- (- 3 - 7 x + 3 x^2)/((1 + x) (x - 1)^2), {x, 0, 70}], x] (* Vincenzo Librandi, Sep 17 2013 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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