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 A361258 #36 Apr 02 2023 12:47:39 %S A361258 2,3,4,1,2,7,8,1,4,5,6,3,2,11,12,1,4,9,10,3,6,7,8,5,2,15,16,1,4,13,14, %T A361258 3,6,11,12,5,8,9,10,7,2,19,20,1,4,17,18,3,6,15,16,5,8,13,14,7,10,11, %U A361258 12,9,2,23,24,1,4,21,22,3,6,19,20,5,8,17,18,7,10,15,16,9,12,13,14,11 %N A361258 Irregular triangle read by rows in which row n lists the print order of a 4n-page booklet. %C A361258 Row n is a permutation of the first 4*n positive integers. %H A361258 Alois P. Heinz, <a href="/A361258/b361258.txt">Rows n = 1..100, flattened</a> %e A361258 Triangle begins: %e A361258 2, 3, 4, 1; %e A361258 2, 7, 8, 1, 4, 5, 6, 3; %e A361258 2, 11, 12, 1, 4, 9, 10, 3, 6, 7, 8, 5; %e A361258 2, 15, 16, 1, 4, 13, 14, 3, 6, 11, 12, 5, 8, 9, 10, 7; %e A361258 ... %p A361258 T:= n-> seq([2*m, 4*n-2*m+1, 4*n-2*m+2, 2*m-1][], m=1..n): %p A361258 seq(T(n), n=1..6); # _Alois P. Heinz_, Mar 06 2023 %Y A361258 Cf. A008586 (row lengths), A033585 (row sums). %K A361258 nonn,look,tabf %O A361258 1,1 %A A361258 _Ole Palnatoke Andersen_, Mar 06 2023