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 A347361 #33 Oct 29 2021 09:08:35 %S A347361 0,0,1,0,3,0,5,0,4,1,9,0,11,3,6,0,15,0,17,0,9,7,21,0,18,9,13,0,27,0, %T A347361 29,0,17,13,24,0,35,15,21,0,39,0,41,3,16,19,45,0,40,6,29,5,51,0,37,0 %N A347361 Number of widths that are zero in the symmetric representation of sigma(n). %C A347361 a(n) is also the number of columns without ON square cells in the ziggurat diagram of n. Both diagrams can be unified in a three-dimensional version. %C A347361 a(n) is also the number of zeros in the n-th row of A249351. %C A347361 The number of widths in the symmetric representation of sigma(n) is equal to 2*n - 1 = A005408(n-1). %C A347361 The sum of the widths of the symmetric representation of sigma(n) equals A000203(n). %C A347361 a(n) = 0, if and only if A237271(n) = 1. %C A347361 a(p) = p - 2, if p is prime. %C A347361 For the definition of "width" see A249351. %F A347361 a(n) = A005408(n-1) - A347273(n). %Y A347361 Indices of zeros give A174973 and also A238443. %Y A347361 Cf. A000040, A005408, A196020, A235791, A236106, A237270, A237271, A237591, A237593, A249351 (widths), A253258, A347273. %K A347361 nonn,more %O A347361 1,5 %A A347361 _Omar E. Pol_, Aug 29 2021