This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A271938 #13 Aug 02 2025 13:45:37
%S A271938 1,3,3,27,19683,
%T A271938 87189642485960958202911070585860771696964072404731750085525219437990967093723439943475549906831683116791055225665627
%N A271938 a(1) = 1, a(2) = 3, a(n) = a(n-1)^a(n-2).
%t A271938 a[1] = 1; a[2] = 3; a[n_] := a[n] = a[n - 1]^a[n - 2]; Array[a, {6}] (* _Michael De Vlieger_, Apr 17 2016 *)
%t A271938 nxt[{a_,b_}]:={b,b^a}; NestList[nxt,{1,3},5][[;;,1]] (* _Harvey P. Dale_, Aug 02 2025 *)
%Y A271938 Cf. A264932 with a(n-1)^^a(n-2) or a(n-1)^a(n-2)^a(n-2);
%Y A271938 Cf. A051285 (with a(2) = 2).
%K A271938 nonn
%O A271938 1,2
%A A271938 _Natan Arie Consigli_, Apr 17 2016