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 A128090 #12 Feb 15 2022 08:58:51 %S A128090 1,-4,4,-18,-18,9,-48,-48,-48,16,-100,-100,-100,-100,25,-180,-180, %T A128090 -180,-180,-180,36,-294,-294,-294,-294,-294,-294,49 %N A128090 Denominators in inverse of A128077, numerators = 1. %C A128090 Row sums of the inverse of A128077: (1/1; -1/4, 1/4; -1/18, -1/18, 1/9; ...) = (1, 0, 0, 0, ...). %C A128090 Row sums of unsigned terms: (1; 4, 4; 18, 18, 9; ...) = A128091. %C A128090 A045991 = (0, 0, 4, 18, 48, 100, ...). %F A128090 Denominators in inverse triangular matrix of A128077, i.e., inverse of (1; 1, 4; 1, 2, 9; 1, 2, 3, 16; ...). %e A128090 First few rows of the triangle: %e A128090 1 %e A128090 -4, 4; %e A128090 -18, -18, 9; %e A128090 -48, -48, -48, 16; %e A128090 -100, -100, -100, -100, 25; %e A128090 ... %Y A128090 Cf. A128077, A045991, A128091. %K A128090 tabl,frac,sign,more %O A128090 1,2 %A A128090 _Gary W. Adamson_, Feb 14 2007