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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

Table of n, a(n) for n=0..23.

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 15 17:03 EST 2019. Contains 330000 sequences. (Running on oeis4.)