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A189376
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Expansion of 1/((1-x)^5*(x^3+x^2+x+1)^2).
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4
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1, 3, 6, 10, 17, 27, 40, 56, 78, 106, 140, 180, 230, 290, 360, 440, 535, 645, 770, 910, 1071, 1253, 1456, 1680, 1932, 2212, 2520, 2856, 3228, 3636, 4080, 4560, 5085, 5655, 6270, 6930, 7645, 8415, 9240, 10120, 11066, 12078
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OFFSET
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0,2
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COMMENTS
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The Gi2 triangle sums of A139600 lead to the sequence given above, see the formulas. For the definitions of the Gi2 and other triangle sums see A180662.
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (3,-3,1,2,-6,6,-2,-1,3,-3,1).
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FORMULA
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a(0)=1, a(1)=3, a(2)=6, a(3)=10, a(4)=17, a(5)=27, a(6)=40, a(7)=56, a(8)=78, a(9)=106, a(10)=140, a(n)=3*a(n-1)-3*a(n-2)+a(n-3)+ 2*a(n-4)- 6*a(n-5)+6*a(n-6)-2*a(n-7)-a(n-8)+3*a(n-9)-3*a(n-10)+a(n-11). - Harvey P. Dale, Apr 12 2015
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MAPLE
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a:= n-> coeff (series (1/((1-x)^5*(x^3+x^2+x+1)^2), x, n+1), x, n):
seq (a(n), n=0..50);
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MATHEMATICA
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CoefficientList[Series[1/((1-x)^5(x^3+x^2+x+1)^2), {x, 0, 50}], x] (* or *) LinearRecurrence[{3, -3, 1, 2, -6, 6, -2, -1, 3, -3, 1}, {1, 3, 6, 10, 17, 27, 40, 56, 78, 106, 140}, 50] (* Harvey P. Dale, Apr 12 2015 *)
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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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