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 A131928 a(n) = phi(binomial(2*n,n)*n). 0
 0, 1, 4, 16, 96, 288, 1440, 5760, 23040, 92160, 552960, 1658880, 7299072, 36495360, 109486080, 510935040, 2043740160, 7664025600, 28740096000, 114960384000, 459841536000, 1839366144000, 8583708672000, 38626689024000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS MAPLE with(numtheory):with(combinat):a:=n->phi(binomial(2*n, n)*n): seq(a(n), n=0..25); MATHEMATICA Table[EulerPhi[Binomial[2n, n]n], {n, 0, 30}] (* Harvey P. Dale, Apr 15 2012 *) CROSSREFS Cf. A000010, A005430 Apery numbers: n*C(2n, n). Sequence in context: A050913 A096243 A263565 * A229138 A098580 A317998 Adjacent sequences: A131925 A131926 A131927 * A131929 A131930 A131931 KEYWORD nonn AUTHOR Zerinvary Lajos, Oct 05 2007 STATUS approved

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Last modified December 6 18:28 EST 2022. Contains 358644 sequences. (Running on oeis4.)