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 A275895 #30 Jan 11 2022 12:35:30 %S A275895 0,2,4,1,3,8,10,12,14,5,7,18,6,21,9,24,26,28,30,11,13,34,36,38,40,15, %T A275895 17,44,16,47,19,50,52,20,55,57,59,22,62,23,65,27,25,69,71,73,75,77,29, %U A275895 31,81,83,85,32,88,33,91,37,35,95,97,99,101,39,104,106,41,109,42,112,43,115,117,119,45,122 %N A275895 "Greedy Queens" permutation of the nonnegative integers. %C A275895 This permutation is produced by a simple greedy algorithm: starting from the top left corner of an infinite chessboard placed in the fourth quadrant of the plane, walk along successive antidiagonals and place a queen in the first available position where it is not threatened by any of the existing queens. In other words, this permutation satisfies the condition that p(i+d) <> p(i)+-d for all i and d >= 1. %C A275895 The rows and columns are indexed starting at 0. p(n) = k means that a queen appears in column n in row k. - _N. J. A. Sloane_, Aug 18 2016 %C A275895 All of A065188 (same for positive integers), A065189, A199134, A275884 should really have started at 0 rather than 1. Then the graph of A065188, for example, would be comparable with the graph of A002251. %C A275895 That this is a permutation of the nonnegative integers follows from the proof in A269526 that every row and every column in that array is a permutation of the positive integers. In particular, every row and every column contains a 0 (which translates to a queen in the present sequence). - _N. J. A. Sloane_, Dec 10 2017 %H A275895 N. J. A. Sloane, <a href="/A275895/b275895.txt">Table of n, a(n) for n = 0..9999</a> %H A275895 F. Michel Dekking, Jeffrey Shallit, and N. J. A. Sloane, <a href="https://doi.org/10.37236/8905">Queens in exile: non-attacking queens on infinite chess boards</a>, Electronic J. Combin., 27:1 (2020), #P1.52. %H A275895 N. J. A. Sloane, <a href="/A275895/a275895.txt">Table of n, a(n) for n = 0..49999</a> %F A275895 a(n) = A065188(n+1)-1. %Y A275895 Cf. A065188 (same for positive integers), A065189 (it's inverse), A199134 (indices of a(n) < n), A275884 (complement), A275894 (same for "nonnegative", i.e., this sequence), A275896 (same for A065189), A002251 (Wythoff pairs). %K A275895 nonn %O A275895 0,2 %A A275895 _N. J. A. Sloane_, Aug 23 2016