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 A325910 #36 May 07 2021 05:09:20 %S A325910 0,1,10,1101,11110010,1111111100001101, %T A325910 11111111111111110000000011110010, %U A325910 1111111111111111111111111111111100000000000000001111111100001101 %N A325910 a(n) = ( (-1)^(n-1) * Sum_{k=0..n-1} (-1)^k*10^(2^k) - (1-(-1)^n)/2 )/9. %H A325910 Seiichi Manyama, <a href="/A325910/b325910.txt">Table of n, a(n) for n = 0..10</a> %F A325910 a(n) = -a(n-1) + (10^(2^(n-1)) - 1)/9. %F A325910 a(n) = A007088(A325912(n-1) - (n mod 2)) for n > 0. %e A325910 1 = -0 + 1. %e A325910 10 = -1 + 11. %e A325910 1101 = -10 + 1111. %e A325910 11110010 = -1101 + 11111111. %e A325910 1111111100001101 = -11110010 + 1111111111111111. %e A325910 ================================================ %e A325910 n | (a(n))_2 | A325912(n-1) %e A325910 --+------------------------------+------------- %e A325910 1 | 1 = 1 | 2 %e A325910 2 | (10)_2 = 2 | 2 %e A325910 3 | (1101)_2 = 13 | 14 %e A325910 4 | (11110010)_2 = 242 | 242 %e A325910 5 | (1111111100001101)_2 = 65293 | 65294 %t A325910 a[n_] := ((-1)^(n - 1) * Sum[(-1)^k * 10^(2^k), {k, 0, n - 1} ] - (1 - (-1)^n)/2)/9; Array[a, 8, 0] (* _Amiram Eldar_, May 07 2021 *) %o A325910 (PARI) {a(n) = ((-1)^(n-1)*sum(k=0, n-1, (-1)^k*10^2^k)-(1-(-1)^n)/2)/9} %Y A325910 Cf. A002275, A007088, A325906, A325912. %K A325910 nonn %O A325910 0,3 %A A325910 _Seiichi Manyama_, Sep 08 2019