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 A274318 #18 Mar 07 2020 13:50:20
%S A274318 1,4,6,5,2,10,8,3,7,9,16,26,29,22,20,23,28,38,12,32,46,13,14,11,15,56,
%T A274318 35,58,47,48,24,18,21,69,17,52,41,19,82,83,70,25,30,62,93,27,65,106,
%U A274318 78,102,37,110,112,76,116,119,92,31,34,49,39,101,33,36,138
%N A274318 Main diagonal of infinite Sudoku-type array A269526.
%C A274318 Conjectured to be a permutation of the natural numbers.
%H A274318 Alois P. Heinz, <a href="/A274318/b274318.txt">Table of n, a(n) for n = 1..1000</a>
%H A274318 F. Michel Dekking, Jeffrey Shallit, and N. J. A. Sloane, <a href="https://www.combinatorics.org/ojs/index.php/eljc/article/view/v27i1p52/8039">Queens in exile: non-attacking queens on infinite chess boards</a>, Electronic J. Combin., 27:1 (2020), #P1.52.
%t A274318 A[n_, k_] := A[n, k] = If[n == 1 && k == 1, 1, s = {Table[A[i, k], {i, 1, n - 1}], Table[A[n, j], {j, 1, k - 1}], Table[A[n - t, k - t], {t, 1, Min[n, k] - 1}], Table[A[n + j, k - j], {j, 1, k - 1}]} // Flatten; For[m = 1, True, m++, If[FreeQ[s, m], Return[m]]]];
%t A274318 a[n_] := A[n, n];
%t A274318 Array[a, 65] (* _Jean-François Alcover_, Jun 10 2017, after _Alois P. Heinz_ *)
%Y A274318 Cf. A269526, A274315, A274316, A274317.
%K A274318 nonn
%O A274318 1,2
%A A274318 _N. J. A. Sloane_, Jun 29 2016
%E A274318 More terms from _Alois P. Heinz_, Jun 29 2016