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 A325493 #30 Sep 15 2019 10:51:57
%S A325493 0,10,1010,11011010,1111001011011010,11111111000011011111001011011010,
%T A325493 1111111111111111000000001111001011111111000011011111001011011010
%N A325493 a(n) = Sum_{k=1..n} A325910(k) * 10^(2^(k-1)).
%H A325493 Seiichi Manyama, <a href="/A325493/b325493.txt">Table of n, a(n) for n = 0..9</a>
%o A325493 (PARI) {a(n) = sum(i=1, n, 10^2^(i-1)*((-1)^(i-1)*sum(j=0, i-1, (-1)^j*10^2^j)-(1-(-1)^i)/2)/9)}
%Y A325493 Cf. A309597, A325910.
%K A325493 nonn
%O A325493 0,2
%A A325493 _Seiichi Manyama_, Sep 14 2019