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 A134831 #7 Jul 01 2023 09:15:04
%S A134831 1,1,2,0,12,-26,312,-1338,16684,-104994,1463904,-12138218,190104132,
%T A134831 -1956240066,34206491416,-420374124426,8140714373532,-116318340148898,
%U A134831 2474986205007504,-40312051604277354
%N A134831 Alternating row sums of triangle A134830.
%F A134831 a(n) = Sum_{k=1..n+1} A134830(n,k)*(-1)^(k-1), n>=0.
%Y A134831 Cf. A134830.
%K A134831 sign,easy
%O A134831 0,3
%A A134831 _Wolfdieter Lang_, Jan 21 2008