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A025269
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a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5.
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0
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2, 1, 1, 1, 6, 27, 122, 555, 2530, 11564, 52994, 243467, 1121292, 5176432, 23952042, 111076279, 516217844, 2404051080, 11218106730, 52447788512, 245659502752, 1152673780946, 5417690242696, 25505048506311, 120257626246616, 567864679387562
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OFFSET
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1,1
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LINKS
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FORMULA
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Conjecture: n*a(n) +4*(-2*n+3)*a(n-1) +12*(n-3)*a(n-2) +6*(2*n-9)*a(n-3) +16*(n-6)*a(n-4)=0. - R. J. Mathar, Nov 21 2014
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MATHEMATICA
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nmax = 30; aa = ConstantArray[0, nmax]; aa[[1]] = 2; aa[[2]] = 1; aa[[3]] = 1; aa[[4]] = 1; Do[aa[[n]] = Sum[aa[[k]]*aa[[n-k]], {k, 1, n-1}], {n, 5, nmax}]; aa (* Vaclav Kotesovec, Jan 25 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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