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 A128046 #10 Feb 08 2023 10:10:58 %S A128046 1,-3,3,0,-5,5,0,0,-7,7,0,0,0,-9,9,0,0,0,0,-11,11,0,0,0,0,0,-13,13,0, %T A128046 0,0,0,0,0,-15,15,0,0,0,0,0,0,0,-17,17,0,0,0,0,0,0,0,0,-19,19,0,0,0,0, %U A128046 0,0,0,0,0,-21,21,0,0,0,0,0,0,0,0,0,0,-23,23 %N A128046 Triangle read by rows: inverse of the lower triangular matrix (1/1; 1/1, 1/3; 1/1, 1/3, 1/5; ...). %C A128046 A version of an odd number transform. %F A128046 Triangle read by rows, replace the right border (1, 2, 3, ...) of A126615 with (1, 3, 5, ...) and the adjacent diagonal (-2, -3, -4, ...) with (-3, -5, -7, ...). %e A128046 First few rows of the triangle: %e A128046 1; %e A128046 -3, 3; %e A128046 0, -5, 5; %e A128046 0, 0, -7, 7; %e A128046 ... %o A128046 (PARI) tabl(nn) = 1/matrix(nn,nn,i,j,if(i>=j, 1/(2*j-1), 0)); %o A128046 lista(nn) = my(m=tabl(nn)); for (n=1, nn, for (k=1, n, print1(m[n,k], ", "))); \\ _Michel Marcus_, Feb 08 2023 %Y A128046 Cf. A126615. %K A128046 tabl,sign %O A128046 1,2 %A A128046 _Gary W. Adamson_, Feb 11 2007 %E A128046 Edited by _N. J. A. Sloane_, Feb 26 2007 %E A128046 More terms from _Michel Marcus_, Feb 08 2023