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A213829
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Principal diagonal of the convolution array A213828.
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4
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2, 28, 114, 296, 610, 1092, 1778, 2704, 3906, 5420, 7282, 9528, 12194, 15316, 18930, 23072, 27778, 33084, 39026, 45640, 52962, 61028, 69874, 79536, 90050, 101452, 113778, 127064, 141346, 156660, 173042
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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 - 3*n^2 + 3*n^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) = 2*x*(1 + 10*x + 7*x^2) and g(x) = (1-x)^4.
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MATHEMATICA
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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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