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A075878
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Sum of coefficients of (x1)^(2i(1))*(x2)^(2i(2))*(x3)^(2i(3))*(x4)^(2i(4)) for {(i1),(i2),(i3),(i4)}=0,1,2,... : sum(i)=2n in the expansion of (x1+x2+x3+x4)^(2n) where n=1,2,3,...
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1
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4, 40, 544, 8320, 131584, 2099200, 33562624, 536903680, 8590065664, 137439477760, 2199025352704, 35184380477440
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OFFSET
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0,1
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COMMENTS
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For k=3, the sequence divided by 3 is equal to A066443.
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LINKS
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FORMULA
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a(n, 4) = 2^(1-4)*(sum(r=0 to Floor((4-1)/2))Binomial(4, r)*(4-2*r)^2n a(n, k) = 2^(1-k)*(sum(r=0 to Floor((k-1)/2))Binomial(k, r)*(k-2*r)^2n for k=1, 2, 3, 4, ...
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CROSSREFS
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Essentially same as A092812. - Kang Seonghoon (lifthrasiir(AT)gmail.com), Oct 09 2008
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KEYWORD
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easy,nonn
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AUTHOR
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Jan Hagberg (jan.hagberg(AT)stat.su.se), Oct 16 2002
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EXTENSIONS
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STATUS
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approved
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