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 A291957 #18 Sep 07 2017 02:46:09 %S A291957 1,0,1,0,-1,0,1,1,0,0,-1,0,-1,0,0,1,1,1,0,0,-1,-1,0,-1,1,0,0,2,0,0,0, %T A291957 -2,-2,0,1,0,0,2,1,-1,0,2,0,0,0,0,-2,-1,-1,0,0,1,2,0,-1,0,1,-2,0,2,1, %U A291957 0,-3,-1,0,0,-1,0,2,3,1,-1,0,0,1,-2,0,1,0,0,-3,0 %N A291957 Triangle read by rows: T(n,k) = T(n-k,k-1) - T(n-k,k) + T(n-k,k+1) with T(0,0) = 1 for 0 <= k <= A003056(n). %H A291957 Seiichi Manyama, <a href="/A291957/b291957.txt">Rows n = 0..481, flattened</a> %e A291957 First few rows are: %e A291957 1; %e A291957 0, 1; %e A291957 0, -1; %e A291957 0, 1, 1; %e A291957 0, 0, -1; %e A291957 0, -1, 0; %e A291957 0, 1, 1, 1; %e A291957 0, 0, -1, -1; %e A291957 0, -1, 1, 0; %e A291957 0, 2, 0, 0; %e A291957 0, -2, -2, 0, 1. %Y A291957 Row sums give A291958. %Y A291957 Columns 0-1 give A000007, (-1)*A111165 (for n>0). %K A291957 sign,tabf %O A291957 0,28 %A A291957 _Seiichi Manyama_, Sep 06 2017