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Tower of 6s mod n.
9

%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