%I #14 Nov 15 2021 01:27:48
%S 1,1,2,2,8,2,12,8,12,8,80,8,96,12,64,64,1024,12,216,64,96,80,1760,64,
%T 1280,96,216,96,2688,64,1920,1024,1280,1024,1536,96,3456,216,1536,
%U 1024,40960,96,4032,1280,1536,1760,80960,1024,4032,1280,32768,1536,79872,216
%N Product of iterated phi(n).
%C A logarithmic plot of this sequence shows an unusual banded structure.
%H T. D. Noe, <a href="/A092694/b092694.txt">Table of n, a(n) for n=1..10000</a>
%H T. D. Noe, <a href="/A092694/a092694.gif">Plot of A092694</a>
%F a(1) = 1, a(n) = phi(n) * a(phi(n))
%e a(100) = 40960 because the iterations of phi (40, 16, 8, 4, 2, 1) have a product of 40960.
%t nMax=100; a=Table[1, {nMax}]; Do[e=EulerPhi[n]; a[[n]]=e*a[[e]], {n, 2, nMax}]; a
%o (Haskell)
%o a092694 n = snd $ until ((== 1) . fst) f (a000010 n, 1) where
%o f (x, p) = (a000010 x, p * x)
%o -- _Reinhard Zumkeller_, Jan 30 2014
%o (Python)
%o from sympy import totient
%o from math import prod
%o def f(n):
%o m = n
%o while m > 1:
%o m = totient(m)
%o yield m
%o def A092694(n): return prod(f(n)) # _Chai Wah Wu_, Nov 14 2021
%Y Cf. A003434 (iterations of phi(n) needed to reach 1), A092693 (iterated phi sum).
%Y Cf. A000010.
%K nonn,look
%O 1,3
%A _T. D. Noe_, Mar 04 2004