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A356341
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a(n) = Sum_{k=1..n} binomial(2*n, k) * sigma(k).
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0
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2, 22, 131, 806, 3607, 20395, 84254, 422230, 1842359, 8616007, 33843614, 173724659, 676938316, 2983855666, 12806013721, 57981927158, 223432922515, 1040923729567, 4004885305320, 18277809794671, 75668287229078, 317458937099194, 1215454524390767, 5785782106653667
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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) ~ Pi^2 * n * 4^(n-1) / 3.
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MATHEMATICA
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Table[Sum[Binomial[2*n, k]*DivisorSigma[1, k], {k, 1, n}], {n, 1, 30}]
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PROG
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(PARI) a(n) = sum(k=1, n, binomial(2*n, k) * sigma(k)); \\ Michel Marcus, Aug 05 2022
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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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