%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