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 A167430 #4 Apr 06 2020 20:39:22 %S A167430 1,2,1,3,2,4,1,3,5,2,4,6,1,3,5,7,2,4,6,8,1,3,5,7,9,2,4,6,8,10,1,3,5,7, %T A167430 9,11,2,4,6,8,10,12,1,3,5,7,9,11,13,2,4,6,8,10,12,14,1,3,5,7,9,11,13, %U A167430 15,2,4,6,8,10,12,14,16,1,3,5,7,9,11,13,15,17,2,4,6,8,10,12,14,16,18,1,3,5,7 %N A167430 Fractal sequence of the interspersion A163255. %C A167430 Both the upper trim and the lower trim of A167430 are identical to A167430. %C A167430 (The upper trim of a fractal sequence s is what remains after the first %C A167430 occurrence of each term is deleted; the lower trim of s is what remains %C A167430 after all 0's are deleted from the sequence s-1.) %F A167430 The sequence is formed by concatenating rows: %F A167430 Row 1: ... 1 2 %F A167430 Row 2: ... 1 3 2 4 %F A167430 Row 3: ... 1 3 5 2 4 6 %F A167430 Row n comes from row n-1 by putting 2n-1 just before 2 and 2*n %F A167430 just after 2n-2. %Y A167430 Cf. A002260, A163255. %K A167430 nonn %O A167430 1,2 %A A167430 _Clark Kimberling_, Nov 03 2009