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 A071676 #5 Mar 10 2018 05:37:43 %S A071676 1,0,1,0,1,1,0,-1,2,1,0,0,-1,3,1,0,0,-2,0,4,1,0,0,1,-5,2,5,1,0,0,0,0, %T A071676 -8,5,6,1,0,0,0,3,-5,-10,9,7,1,0,0,0,-1,8,-15,-10,14,8,1,0,0,0,0,2,11, %U A071676 -30,-7,20,9,1,0,0,0,0,-4,15,6,-49,0,27,10,1,0,0,0,0,1,-10,41,-14,-70,12,35,11,1,0,0,0,0,0,-5,-6,77,-56,-90,30,44 %N A071676 Array read by antidiagonals of signed variant of trinomial coefficients with T(n,k)=T(n-1,k)+T(n-1,k-1)-T(n-1,k-2) starting with T(0,0)=1. %C A071676 Each column is eventually positive, i.e. for each k there is a number j(k) such that T(n,k) is positive for all n>=j(k). Despite this, each row sum is 1. %e A071676 Rows start: %e A071676 1, 0, 0, 0, 0, ...; %e A071676 1, 1, -1, 0, 0, 0, ...; %e A071676 1, 2, -1, -2, 1, 0, 0, ...; %e A071676 1, 3, 0, -5, 0, 3, -1, 0, ...; %e A071676 1, 4, 2, -8, -5, 8, 2, -4, 1, ...; %e A071676 etc... %Y A071676 Cf. A071675. %K A071676 sign,tabl %O A071676 0,9 %A A071676 _Henry Bottomley_, May 30 2002