%I #2 Mar 30 2012 19:00:24
%S 1,1,2,15,30517578124
%N a(1) = 1, for n >= 2: a(n) = n^(a(n-1)) - 1.
%C The next term is too large to include.
%e For n = 4: a(4) = 4^2 - 1 = 15.
%K nonn
%O 1,3
%A _Jaroslav Krizek_, Nov 03 2010