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A108360
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Expansion of (1-2x)^2/((1-x)^2(1-2x-x^2)^2).
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1
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1, 2, 5, 12, 30, 76, 194, 496, 1267, 3230, 8215, 20844, 52768, 133304, 336100, 845888, 2125381, 5332058, 13357833, 33419820, 83510018, 208437060, 519691110, 1294430448, 3221081335, 8008262966, 19893476315, 49378623564, 122473408452
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OFFSET
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0,2
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COMMENTS
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Row sums of number triangle A108359.
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LINKS
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FORMULA
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G.f.: (1-4x+4x^2)/(1-6x+11x^2-4x^3-5x^4+2x^5+x^6); a(n)=sum{k=0..n, sum{j=0..n-k, C(k, j)C(n-j, k)*floor((j+2)/2)}}.
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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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