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A108296
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Diagonal sums of the number triangle associated to A086617.
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2
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1, 1, 2, 3, 5, 8, 14, 24, 43, 78, 144, 269, 509, 971, 1868, 3618, 7049, 13805, 27162, 53661, 106405, 211697, 422458, 845386, 1696017, 3410522, 6873060, 13878721, 28077439, 56900936, 115501012, 234807488, 478032437, 974507543, 1989123814
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OFFSET
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0,3
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COMMENTS
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LINKS
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FORMULA
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G.f.: (1-x^2-sqrt(1-2x^2-4x^3-3x^4))/(2*x^3(1-x^2)); a(n)=sum{k=0..floor(n/2), sum{j=0..n-2k, C(n-2k, j)C(k, j)C(j)}.
Conjecture: (n+3)*a(n) +(-n-2)*a(n-1) +2*(-n-1)*a(n-2) +2*(-n+3)*a(n-3) +(n+1)*a(n-4) +3*(n-2)*a(n-5)=0. - R. J. Mathar, Nov 16 2012
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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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