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 A272188 #20 Apr 29 2016 09:20:00 %S A272188 1,0,1,3,0,1,2,3,5,0,1,2,3,4,5,7,0,1,2,3,4,5,6,7,9,0,1,2,3,4,5,6,7,8, %T A272188 9,11,0,1,2,3,4,5,6,7,8,9,10,11,13,0,1,2,3,4,5,6,7,8,9,10,11,12,13,15, %U A272188 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,17 %N A272188 Triangle with 2*n+1 terms per row, read by rows: the first row is 1 (by decree), following rows contain 0 to 2n+1 but omitting 2n. %C A272188 Row n is row 2n+1 of A128138, a bisection. %C A272188 The second bisection by rows %C A272188 0, 2, %C A272188 0, 1, 2, 4, %C A272188 0, 1, 2, 3, 4, 6, %C A272188 0, 1, 2, 3, 4, 5, 6, 8, %C A272188 etc %C A272188 is the basis of %C A272188 0, 2, 4, 6, 8, 10, 12, ... the even numbers A005843(n) %C A272188 0, 1, 2, 4, 3, 6, 8, 5, 10, ... a permutation of the nonnegative integers A265667(n). %C A272188 0, 1, 2, 3, 4, 6, 5, 8, 7, 10, 12, ... a permutation of the nonnegative integers A265734(n) %C A272188 etc. %C A272188 A005843(n) - A005843(n-1) = 2, for n>0. %C A272188 A265667(n) - A265667(n-3) = 4, 2, 4 (period 3), for n>2. %C A272188 A265734(n) - A265734(n-5) = 6, 4, 6, 4, 6 (period 5), for n>4. %C A272188 See A267654. %C A272188 For %C A272188 1, 3, 5, 7, 9, 11, 13 ... the odd numbers A005408(n), %C A272188 0, 1, 3, 2, 5, 7, 4, 9, 11, ... a permutation of the nonnegative numbers A006369, %C A272188 0, 1, 2, 3, 5, 4, 7, 6, 9, 11, 8, 13, 10, 15, ... another permutation, %C A272188 a(n) must be extended with one term by row: %C A272188 1, 3, %C A272188 0, 1, 3, 2, %C A272188 0, 1, 2, 3, 5, 4, %e A272188 Irregular triangle: %e A272188 1, %e A272188 0, 1, 3, %e A272188 0, 1, 2, 3, 5, %e A272188 0, 1, 2, 3, 4, 5, 7, %e A272188 0, 1, 2, 3, 4, 5, 6, 7, 9, %e A272188 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, %e A272188 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, %e A272188 etc. %t A272188 Table[Delete[Range[0, 2 n + 1], 2 n + 1], {n, 0, 8}] // Flatten (* _Michael De Vlieger_, Apr 25 2016 *) %Y A272188 Cf. A001477, A005408, A005843, A006369, A028310 (main diagonal), A053186, A265667, A265734, A267654. %K A272188 nonn,tabf,easy %O A272188 0,4 %A A272188 _Paul Curtz_, Apr 22 2016