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 A160386 #27 Jun 11 2023 02:54:26
%S A160386 2,3,4,4,1,5,5,0,8,6,7,4,8,6,4,6,1,4,4,1,3,4,1,5,4,7,4,3,4,5,6,0,4,5,
%T A160386 9,7,6,1,4,7,2,4,5,6,3,9,0,6,6,9,3,0,2,7,6,7,9,4,2,7,7,3,7,0,9,8,3,8,
%U A160386 1,4,3,1,5,1,3,7,5,8,5,3,5,3,1,0,3,7,5,6,5,6,5,9,8,4,9,7,6,5,9,8,4,4,0,6,4
%N A160386 Decimal expansion of Sum_{n>=0}(-1)^n/3^(2^n).
%C A160386 This sum is among forms which Kempner showed are transcendental. - _Kevin Ryde_, Sep 16 2019
%H A160386 Harry J. Smith, <a href="/A160386/b160386.txt">Table of n, a(n) for n = 0..20000</a>
%H A160386 Aubrey J. Kempner, <a href="https://www.jstor.org/stable/1988833">On Transcendental Numbers</a>, Transactions of the American Mathematical Society, Vol. 17, No. 4 (October 1916), pp. 476-482.
%H A160386 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A160386 0.234415508674864614413415474345604597614724563906693027679427737098381...
%t A160386 RealDigits[N[Sum[(-1)^n/3^(2^n), {n, 0, Infinity}], 120]][[1]] (* _Amiram Eldar_, Jun 11 2023 *)
%o A160386 (PARI) { default(realprecision, 20080); x=10*suminf(n=0, (-1)^n/3^(2^n)); for (n=0, 20000, d=floor(x); x=(x-d)*10; write("b160386.txt", n, " ", d)); }
%Y A160386 Cf. A006467 (continued fraction), A030300 (ternary expansion).
%K A160386 nonn,cons
%O A160386 0,1
%A A160386 _Harry J. Smith_, May 12 2009