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 A355906 #19 Sep 29 2022 05:17:26 %S A355906 0,0,-3,3,-6,9,-15,21,-33,48,-75,111,-168,252,-381,570,-858,1287, %T A355906 -1932,2898,-4350,6525,-9789,14682,-22026,33039,-49560,74340,-111513, %U A355906 167268,-250905,376356,-564537,846804,-1270209,1905312,-2857971,4286955,-6430434,9645651 %N A355906 a(0) = 0; for n >= 1, a(n) = -(3/2)*(a(n-1)+A355905(n-1)). %C A355906 When n is odd, a(n) is the largest multiple of 3 whose NST representation has n digits. When n is even, a(n) is the smallest multiple of 3 with that property. %H A355906 Don Knuth, <a href="http://cs.stanford.edu/~knuth/papers/ambidextrous.pdf">Ambidextrous Numbers</a>, Preprint, September 2022. See b_n, (7.3). %Y A355906 Cf. A355904, A355905, A355907-A355913. %K A355906 sign %O A355906 0,3 %A A355906 _N. J. A. Sloane_, Sep 18 2022 %E A355906 More terms from _Jinyuan Wang_, Sep 29 2022