OFFSET
1,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..300
MAPLE
with(numtheory); seq((2*n)!/(phi(2*n)!)^2, n = 1..20); # G. C. Greubel, Aug 25 2019
PROG
(PARI) for(n=1, 30, print1((2*n)!/(eulerphi(2*n))!^2, ", "))
(Magma) F:=Factorial; [F(2*n)/F(EulerPhi(2*n))^2 : n in [1..20]]; // G. C. Greubel, Aug 25 2019
(Sage) f=factorial; [f(2*n)/f(euler_phi(2*n))^2 for n in (1..20)] # G. C. Greubel, Aug 25 2019
(GAP) F:=Factorial;; List([1..20], n-> F(2*n)/F(Phi(2*n))^2 ); # G. C. Greubel, Aug 25 2019
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Jun 19 2002
STATUS
approved