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 A382281 #5 Mar 21 2025 09:55:45 %S A382281 0,1,1,3,1,3,3,7,1,3,3,11,12,13,13,15,1,3,12,13,3,11,13,15,3,7,13,15, %T A382281 13,15,30,31,1,12,3,13,3,13,11,15,3,13,7,15,13,30,15,31,3,13,13,30,7, %U A382281 15,15,31,11,15,15,31,15,31,31,63,1,3,3,11,12,13,13,15 %N A382281 Let n encode the edges of a graph by taking edges (u,v), with u < v, in colexicographic order ((0,1), (0,2), (1,2), (0,3), ...) and adding each edge to the graph if the corresponding binary digit of n (starting with the least significant digit) is 1. a(n) is the smallest nonnegative integer that encodes the same unlabeled graph as n (disregarding any isolated vertices), i.e., the code of the graph as defined in A076184. %F A382281 a(n) <= n with equality if and only if n is in A076184. %e A382281 n = 6 is 110 in binary, encoding the graph with edges (0,2) and (1,2), i.e., the path graph on 3 vertices. The canonical code of that graph is a(6) = 3, corresponding to the graph with edges (0,1) and (0,2). %Y A382281 Cf. A076184. %K A382281 nonn %O A382281 0,4 %A A382281 _Pontus von Brömssen_, Mar 21 2025