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%I #11 May 10 2021 19:08:44
%S 1,2,3,23,20880467999847912034355032910540
%N a(n) = a(n-1)^a(n-1) - a(n-2)^a(n-2) with a(0)=1 and a(1)=2.
%C a(6) is too large to include.
%e 23^23 - 3^3 = 20880467999847912034355032910540.
%t a[0] := 1; a[1] := 2; a[n_] := a[n] = a[n - 1]^a[n - 1] - a[n - 2]^a[n - 2]; Table[Floor[a[n]], {n, 0, 4}] (* _G. C. Greubel_, Dec 20 2017 *)
%t nxt[{a_,b_}]:={b,b^b-a^a}; NestList[nxt,{1,2},4][[All,1]]//Quiet (* _Harvey P. Dale_, May 10 2021 *)
%K easy,nonn
%O 0,2
%A _Giovanni Teofilatto_, Feb 26 2006
%E Definition corrected and example added by _N. J. A. Sloane_, Jun 09 2017