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A131928
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a(n) = phi(binomial(2*n,n)*n).
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0
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0, 1, 4, 16, 96, 288, 1440, 5760, 23040, 92160, 552960, 1658880, 7299072, 36495360, 109486080, 510935040, 2043740160, 7664025600, 28740096000, 114960384000, 459841536000, 1839366144000, 8583708672000, 38626689024000
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OFFSET
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0,3
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LINKS
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MAPLE
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with(numtheory):with(combinat):a:=n->phi(binomial(2*n, n)*n): seq(a(n), n=0..25);
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MATHEMATICA
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Table[EulerPhi[Binomial[2n, n]n], {n, 0, 30}] (* Harvey P. Dale, Apr 15 2012 *)
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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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