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 A317197 #7 Aug 05 2018 12:01:08 %S A317197 1,121,1213121,12131211213121,121312112131212131211213121, %T A317197 121312112131212131211213121312112131212131211213121, %U A317197 12131211213121213121121312131211213121213121121312112131212131211213121312112131212131211213121 %N A317197 a(n) is the concatenation of A103269(n-i) for i = 0,1,2,...,n-1. %C A317197 a(n) is a palindrome. %C A317197 A027084 gives lengths of these words. %H A317197 Bo Tan and Zhi-Ying Wen, <a href="http://dx.doi.org/10.1016/j.ejc.2006.07.007">Some properties of the Tribonacci sequence</a>, European Journal of Combinatorics, 28 (2007) 1703-1719. See D_n. %e A317197 a(3) = 1213.12.1 = 1213121. %Y A317197 A027084. %K A317197 nonn %O A317197 1,2 %A A317197 _N. J. A. Sloane_, Aug 05 2018