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A066973
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phi(binomial(2n,n)).
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2
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1, 2, 8, 24, 72, 240, 960, 2880, 15360, 69120, 165888, 912384, 3041280, 9123840, 34062336, 127733760, 479001600, 1596672000, 6386688000, 22992076800, 102187008000, 429185433600, 1755758592000, 6730407936000, 28267713331200
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Harry J. Smith, Table of n, a(n) for n = 1..200
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FORMULA
| a(n) = A000010(A000984(n)).
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MAPLE
| with(numtheory):with(combinat):a:=n->phi(binomial(2*n, n)): seq(a(n), n=1..25); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 05 2007
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MATHEMATICA
| f[n_] := EulerPhi[Binomial[2n, n]]; Table[f[n], {n, 100}] (* Enrique Pérez Herrero, Jan 31 2012 *)
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PROG
| (sage) [euler_phi(binomial(2*n, n))for n in xrange(1, 26)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 06 2009]
(PARI) { for (n=1, 200, write("b066973.txt", n, " ", eulerphi(binomial(2*n, n))) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Apr 12 2010]
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CROSSREFS
| Sequence in context: A050242 A045697 A131569 * A130495 A026070 A093833
Adjacent sequences: A066970 A066971 A066972 * A066974 A066975 A066976
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Jan 26 2002
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