%I #14 Mar 19 2020 16:23:06
%S 0,0,0,0,1,0,1,0,0,6,5,0,1,8,6,0,1,0,1,16,15,16,2,0,6,14,0,8,23,6,1,0,
%T 27,18,1,0,1,20,27,16,18,36,1,16,36,2,36,0,43,6,18,40,47,0,16,8,39,52,
%U 9,36,9,32,36,0,1,60,14,52,48,36,6,0,1,38,6,20
%N Tower of 6s mod n.
%C a(n) = (6^(6^(6^(6^(6^ ... ))))) mod n, provided sufficient 6s are in the tower such that adding more doesn't affect the value of a(n).
%H Wayne VanWeerthuizen, <a href="/A245973/b245973.txt">Table of n, a(n) for n = 1..10000</a>
%o (Sage)
%o def tower6mod(n):
%o if ( n <= 12 ):
%o return 46656%n
%o else:
%o ep = euler_phi(n)
%o return power_mod(6,ep+tower6mod(ep),n)
%Y Cf. A240162, A245970, A245971, A245972, A245974.
%K nonn,easy
%O 1,10
%A _Wayne VanWeerthuizen_, Aug 08 2014