%I #2 Feb 11 2014 19:05:28
%S 1,1,4,18,262160
%N a(1) = a(2) = 1; a(n) = 2^a(n-1) + 2^a(n-2) for n > 2.
%t a[n_] := 1 /; n == 1 a[n_] := 1 /; n == 2 a[n_] := 2^a[n - 1] + 2^a[n - 2] /; n > 2; Table[a[i], {i, 1, 6}]
%K nonn
%O 1,3
%A _Joseph L. Pe_, Apr 23 2002
%E a(6) has 78919 digits.
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