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 A122917 #5 Oct 30 2022 21:19:42 %S A122917 1,-1,1,0,-3,1,1,5,-5,1,-1,-6,14,-7,1,0,6,-29,27,-9,1,1,-6,50,-76,44, %T A122917 -11,1,-1,7,-77,175,-155,65,-13,1,0,-9,111,-351,441,-274,90,-15,1,1, %U A122917 11,-154,638,-1078,924,-441 %N A122917 Riordan array (1/(1+x+x^2),x/(1+x)^2). %C A122917 Row sums are A122918. Inverse is A122919. %e A122917 Triangle begins %e A122917 1, %e A122917 -1, 1, %e A122917 0, -3, 1, %e A122917 1, 5, -5, 1, %e A122917 -1, -6, 14, -7, 1, %e A122917 0, 6, -29, 27, -9, 1, %e A122917 1, -6, 50, -76, 44, -11, 1, %e A122917 -1, 7, -77, 175, -155, 65, -13, 1 %Y A122917 Cf. A122918, A122919. %K A122917 easy,sign,tabl %O A122917 0,5 %A A122917 _Paul Barry_, Sep 19 2006