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A122911
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Expansion of (1+x)*(1-6*x-25*x^2)/((1+2x)(1-4x)(1+8x)(1-16x)).
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0
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1, 5, 139, 1645, 30506, 452860, 7520584, 118102640, 1907343136, 30375432640, 487141579904, 7785180808960, 124635539862016, 1993587347102720, 31902047417780224, 510395557925908480, 8166626525501136896
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OFFSET
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0,2
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COMMENTS
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Let M be the matrix M(n,k)=J(k+1)*sum{j=0..n, (-1)^(n-j)C(n,j)C(j+1,k+1)}. a(n) gives the row sums of M^4.
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LINKS
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FORMULA
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G.f.: (1-5x-31x^2-25x^3)/(1-10x-120x^2+320x^3+1024x^4); a(n)=85*16^n/192+203*(-8)^n/576+55*4^n/288+(-2)^n/72; a(n)=a(n)=J(n)*A122910(n-1)+J(n+1)*A122910(n) where J(n) are the Jacobsthal numbers A001045(n).
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MATHEMATICA
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CoefficientList[Series[(1+x)(1-6x-25x^2)/((1+2x)(1-4x)(1+8x)(1-16x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{10, 120, -320, -1024}, {1, 5, 139, 1645}, 20] (* Harvey P. Dale, Dec 04 2017 *)
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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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