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A213754
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Principal diagonal of the convolution array A213753.
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3
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1, 16, 111, 576, 2631, 11292, 46927, 191680, 775599, 3122076, 12531591, 50220912, 201088855, 804798268, 3220143903, 12882607872, 51534757599, 206148206268, 824612224663, 3298489794160, 13194045161031, 52776361000476
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = -3*2^n + 3*2^(2*n) - n*2^(n+1) - n^2.
a(n) = 11*a(n-1) - 47*a(n-2) + 101*a(n-3) - 116*a(n-4) + 68*a(n-5) - 16*a(n-6) for n>5. Corrected by Colin Barker, Nov 07 2017
G.f.: f(x)/g(x), where f(x) = x*(1 + 5*x - 18*x^2 + 6*x^3 + 12*x^4) and g(x) = (1 - 4*x) * (1 - x)^3 * (1 - 2*x)^2.
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MATHEMATICA
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PROG
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(PARI) Vec(x*(1 + 5*x - 18*x^2 + 6*x^3 + 12*x^4) / ((1 - x)^3*(1 - 2*x)^2*(1 - 4*x)) + O(x^30)) \\ Colin Barker, Nov 07 2017
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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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