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 A153659 #11 Jul 15 2025 12:21:12 %S A153659 1,1,1,1,0,1,2,1,0,1,1,0,0,0,1,3,1,1,0,0,1,1,0,0,0,0,0,1,4,2,0,1,0,0, %T A153659 0,1,2,0,1,0,0,0,0,0,1,3,1,0,0,1,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,1,8,3, %U A153659 2,1,0,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,1,3,1,0,0,0,0,1,0,0,0,0,0,0,1 %N A153659 Triangle read by rows. A074206 interleaved with k-1 zeros in the k-th column. %C A153659 By moving the term in the lower right corner to the upper right corner and then calculating the determinant one gets the sequence 1,-1,-1,-1,-1,-1,-1,-1,... The contributing permutation matrices have the same signs as the contributing permutation matrices in the Möbius function determinant. It is conjectured that their number is A074206. %e A153659 Table begins: %e A153659 1; %e A153659 1,1; %e A153659 1,0,1; %e A153659 2,1,0,1; %e A153659 1,0,0,0,1; %e A153659 3,1,1,0,0,1; %e A153659 1,0,0,0,0,0,1; %e A153659 4,2,0,1,0,0,0,1; %e A153659 2,0,1,0,0,0,0,0,1; %e A153659 3,1,0,0,1,0,0,0,0,1; %e A153659 ... %o A153659 (Excel) =if(mod(row();column())=0;lookup(row()/column();A000027;A074206);0) %Y A153659 Cf. A008683, A074206. %K A153659 nonn,tabl %O A153659 1,7 %A A153659 _Mats Granvik_, Dec 30 2008