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 A016066 #16 Sep 05 2017 03:13:52
%S A016066 3,15,1618,528491311,514843556263457213182266,
%T A016066 28511235679461510605581038657982805983853648817939444953417128837
%N A016066 a(n) = round(e^(e^n)).
%C A016066 a(6) is a 176-digit number. - _Jon E. Schoenfield_, Sep 04 2017
%e A016066 a(0) = round(e) = round(2.718281828459...) = 3.
%e A016066 a(1) = round(e^e) = round(15.154262241479264...) = 15.
%e A016066 a(2) = round(e^(e^2)) = round(1618.1779919126535...) = 1618.
%t A016066 Table[Round[E^(E^n)], {n, 0, 5}] (* _Harvey P. Dale_, Oct 21 2016 *)
%Y A016066 Cf. A001113, A073226, A096232, A096404.
%K A016066 nonn,easy
%O A016066 0,1
%A A016066 _Robert G. Wilson v_
%E A016066 Corrected by _N. J. A. Sloane_, Aug 16 2004