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 A128257 #8 Jun 08 2023 08:50:02 %S A128257 1,0,1,2,-1,1,-1,2,-1,1,2,-1,1,-1,1,0,1,0,1,-1,1,2,-1,1,-1,1,-1,1,-2, %T A128257 3,-2,2,-1,1,-1,1,3,-2,2,-1,1,-1,1,-1,1,0,1,0,0,0,1,-1,1,-1,1,2,-1,1, %U A128257 -1,1,-1,1,-1,1,-1,1,-2,3,-2,3,-2,2,-1,1,-1,1,-1,1,2,-1,1,-1,1,-1,1,-1,1,-1,1,-1,1 %N A128257 Inverse Moebius transform of A097807. %C A128257 Row sums = A001227: (1, 1, 2, 1, 2, 2, 2,...), number of odd divisors of n. %F A128257 A051731 * A097807 as infinite lower triangular matrices. %e A128257 First few rows of the triangle are: %e A128257 1; %e A128257 0, 1; %e A128257 2, -1, 1; %e A128257 -1, 2, -1, 1; %e A128257 2, -1, 1, -1, 1; %e A128257 0, 1, 0, 1, -1, 1; %e A128257 ... %Y A128257 Cf. A001227, A051731, A097807. %K A128257 tabl,sign %O A128257 0,4 %A A128257 _Gary W. Adamson_, Feb 21 2007 %E A128257 a(18) = 1 corrected and more terms from _Georg Fischer_, Jun 08 2023