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 A263048 #33 May 02 2023 16:32:11
%S A263048 0,1,1,2,3,17,129145076
%N A263048 a(0)=0, a(1)=1; for n>1, a(n) = a(n-2)^a(n-1) + a(n-1)^a(n-2).
%C A263048 Next term has 365895553 digits.
%t A263048 RecurrenceTable[{a[0] == 0, a[1] == 1, a[n] == a[n-2]^a[n-1]+a[n-1]^a[n-2]}, a, {n, 6}] (* _Vincenzo Librandi_, Oct 09 2015 *)
%t A263048 nxt[{a_,b_}]:={b,a^b+b^a}; NestList[nxt,{0,1},6][[;;,1]] (* _Harvey P. Dale_, May 02 2023 *)
%o A263048 (PARI) a(n) = if(n<2, n, a(n-2)^a(n-1)+a(n-1)^a(n-2)) \\ _Altug Alkan_, Oct 15 2015
%o A263048 (Magma) [n le 2 select n-1 else Self(n-2)^Self(n-1)+Self(n-1)^Self(n-2): n in [1..7]]; // _Vincenzo Librandi_, Oct 09 2015
%K A263048 nonn
%O A263048 0,4
%A A263048 _Gianmarco Giordano_, Oct 08 2015