A104354 - OEIS

%I #21 Apr 08 2024 01:38:30

%S 1,1,2,4,16,48,288,576,1728,8640,86400,259200,3110400,21772800,

%T 108864000,217728000,3483648000,10450944000,188116992000,940584960000,

%U 6584094720000,72425041920000,1593350922240000,4780052766720000,23900263833600000,310703429836800000

%N Euler's totient of A104350(n).

%H Amiram Eldar, <a href="/A104354/b104354.txt">Table of n, a(n) for n = 1..640</a>

%H Reinhard Zumkeller, <a href="/A104350/a104350.txt">Products of largest prime factors of numbers <= n</a>.

%F a(n) = A000010(A104350(n)).

%t EulerPhi[FoldList[Times, Array[FactorInteger[#][[-1, 1]] &, 30]]] (* _Amiram Eldar_, Apr 08 2024 *)

%o (PARI) gpf(n) = my(f=factor(n)[, 1]); f[#f];

%o a(n) = eulerphi(prod(i=2, n, gpf(i))); \\ _Michel Marcus_, Nov 12 2023

%Y Cf. A000010, A048855, A104350.

%K nonn

%O 1,3

%A _Reinhard Zumkeller_, Mar 06 2005

%E a(1) prepended by _Michel Marcus_, Nov 12 2023