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 A107865 #3 Mar 30 2012 18:36:46
%S A107865 1,-1,1,-1,-2,1,-7,-4,-3,1,-77,-26,-9,-4,1,-1145,-287,-67,-16,-5,1,
%T A107865 -21410,-4412,-798,-139,-25,-6,1,-481683,-86004,-13029,-1830,-251,-36,
%U A107865 -7,1,-12655196,-2017658,-268368,-32191,-3667,-412,-49,-8,1,-379998938,-55134458,-6630228,-705680,-69868,-6657,-631
%N A107865 Matrix inverse of triangle A107862.
%C A107865 Matrix product with A107867 equals A107876.
%e A107865 Triangle begins:
%e A107865 1;
%e A107865 -1,1;
%e A107865 -1,-2,1;
%e A107865 -7,-4,-3,1;
%e A107865 -77,-26,-9,-4,1;
%e A107865 -1145,-287,-67,-16,-5,1;
%e A107865 -21410,-4412,-798,-139,-25,-6,1;
%e A107865 -481683,-86004,-13029,-1830,-251,-36,-7,1; ...
%o A107865 (PARI) {T(n,k)=(matrix(n+1,n+1,r,c,if(r>=c, binomial((r-1)*(r-2)/2-(c-1)*(c-2)/2+r-c,r-c)))^-1)[n+1,k+1]}
%Y A107865 Cf. A107862, A107866 (column 0), A107867, A107870, A107876.
%K A107865 sign,tabl
%O A107865 0,5
%A A107865 _Paul D. Hanna_, Jun 04 2005