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A213845
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Principal diagonal of the convolution array A213844.
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3
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3, 32, 119, 296, 595, 1048, 1687, 2544, 3651, 5040, 6743, 8792, 11219, 14056, 17335, 21088, 25347, 30144, 35511, 41480, 48083, 55352, 63319, 72016, 81475, 91728, 102807, 114744, 127571, 141320, 156023, 171712
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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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a(n) = (2*n - 9*n^2 + 16*n^3)/3.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4).
G.f.: f(x)/g(x), where f(x) = x*(3 + 20*x + 9*x^2) and g(x) = (1-x)^4.
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MATHEMATICA
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LinearRecurrence[{4, -6, 4, -1}, {3, 32, 119, 296}, 40] (* Harvey P. Dale, Nov 06 2014 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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