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 A296978 #7 Dec 28 2017 21:36:29 %S A296978 1,1,1,1,2,2,1,1,1,1,1,1,2,1,2,1,1,2,2,1,2,3,1,3,2,2,1,1,2,1,2,2,1,3, %T A296978 2,2,1,2,3,1,3,1,2,3,2,1,1,1,1,1,1,1,1,2,1,1,2,1,1,1,2,2,1,1,2,3,1,1, %U A296978 3,2,1,2,1,1,1,2,1,2,1,2,1,3,1,2,2,1,1 %N A296978 List of normal sequences ordered first by length and then lexicographically, where a finite sequence is normal if it spans an initial interval of positive integers. %F A296978 Row n is formed by A000670(n) sequences and has total length n * A000670(n). %e A296978 Triangle of normal sequences begins: %e A296978 1, %e A296978 11,12,21, %e A296978 111,112,121,122,123,132,211,212,213,221,231,312,321. %t A296978 normseqs[n_]:=Union@@Permutations/@Function[s,Array[Count[s,y_/;y<=#]+1&,n]]/@Subsets[Range[n-1]+1]; %t A296978 Array[normseqs,5,1,Join] %Y A296978 Cf. A000670, A095684, A124734, A228369, A296772, A296975, A296976, A296977. %K A296978 nonn,tabf %O A296978 1,5 %A A296978 _Gus Wiseman_, Dec 22 2017