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A025279
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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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1, 0, -1, 1, 2, 5, 8, 13, 20, 38, 86, 215, 526, 1230, 2762, 6115, 13670, 31294, 73258, 173644, 412612, 978074, 2313060, 5472523, 12989654, 30974176, 74174934, 178173000, 428776280, 1033084378, 2491843724, 6018491615, 14559411886, 35279687544
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OFFSET
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1,5
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LINKS
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FORMULA
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Recurrence: n*a(n) = 2*(2*n-3)*a(n-1) - 4*(n-3)*a(n-2) - 2*(2*n-9)*a(n-3) + 12*(n-6)*a(n-4). - Vaclav Kotesovec, Jan 25 2015
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MATHEMATICA
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nmax = 30; aa = ConstantArray[0, nmax]; aa[[1]] = 1; aa[[2]] = 0; 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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sign
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AUTHOR
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STATUS
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approved
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