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 A039980 #18 Jul 08 2025 22:42:18 %S A039980 1,0,2,1,1,2,0,2,1,1,1,0,0,1,2,2,2,0,0,2,2,1,0,0,1,0,2,1,1,0,0,1,2,2, %T A039980 2,1,0,1,1,2,0,0,2,0,1,2,2,0,0,2,1,1,1,2,0,2,2,1,0,0,1,0,0,1,0,2,1,1, %U A039980 2,0,2,2,1,0,2,1,1,2,0,2,1,1,1,0,0,1,2,2,2,1,0,1,1,2,0,0,2,0,1,2,2,0,0,2,1 %N A039980 An example of a d-perfect sequence. %H A039980 D. Kohel, S. Ling and C. Xing, <a href="http://www.maths.usyd.edu.au/u/kohel/doc/perfect.ps">Explicit Sequence Expansions</a>, in Sequences and their Applications, C. Ding, T. Helleseth, and H. Niederreiter, eds., Proceedings of SETA'98 (Singapore, 1998), 308-317, 1999. DOI: 10.1007/978-1-4471-0551-0_23 %F A039980 a(n) = A108624(n) mod 3. - _Christian G. Bower_, Jun 12 2005 %Y A039980 Cf. A108624. %K A039980 nonn %O A039980 1,3 %A A039980 _N. J. A. Sloane_ %E A039980 More terms from _Christian G. Bower_, Jun 12 2005