OFFSET
0,4
LINKS
Harry J. Smith, Table of n, a(n) for n = 0..200
Florian Luca, Pantelimon Stanica, On the Euler function of the Catalan numbers, Journal of Number Theory 132(7):1404-1424, July 2012.
MAPLE
with(numtheory): a:= n-> phi(binomial(2*n, n)/(n+1)): seq(a(n), n=0..27); # Zerinvary Lajos, Oct 05 2007
PROG
(PARI) a(n) = eulerphi(binomial(2*n, n)/(n + 1));
(Sage) [euler_phi(binomial(2*n, n)/(n+1))for n in range(0, 28)] # Zerinvary Lajos, Jun 06 2009
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Jul 04 2001
STATUS
approved