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 A181653 #5 Sep 29 2018 18:47:26 %S A181653 1,1,1,0,1,1,0,1,1,1,0,0,0,1,1,0,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,1, %T A181653 1,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,1,1 %N A181653 Generalized (conditional) Riordan array with k-th column generated by x^k*(1+x) if k mod 2 = 0, x^k*(1+x+x^2) otherwise. %C A181653 Row sums are A174296. A181654 is an eigentriangle. %e A181653 Triangle begins %e A181653 1; %e A181653 1, 1; %e A181653 0, 1, 1; %e A181653 0, 1, 1, 1; %e A181653 0, 0, 0, 1, 1; %e A181653 0, 0, 0, 1, 1, 1; %e A181653 0, 0, 0, 0, 0, 1, 1; %e A181653 0, 0, 0, 0, 0, 1, 1, 1; %e A181653 0, 0, 0, 0, 0, 0, 0, 1, 1; %e A181653 0, 0, 0, 0, 0, 0, 0, 1, 1, 1; %e A181653 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1; %e A181653 Production matrix begins %e A181653 1, 1; %e A181653 -1, 0, 1; %e A181653 1, 1, 0, 1; %e A181653 0, -1, -1, 0, 1; %e A181653 0, 1, 1, 1, 0, 1; %e A181653 0, 0, 0, -1, -1, 0, 1; %e A181653 0, 0, 0, 1, 1, 1, 0, 1; %e A181653 0, 0, 0, 0, 0, -1, -1, 0, 1; %e A181653 0, 0, 0, 0, 0, 1, 1, 1, 0, 1; %e A181653 0, 0, 0, 0, 0, 0, 0, -1, -1, 0, 1; %K A181653 easy,nonn,tabl %O A181653 0,1 %A A181653 _Paul Barry_, Nov 03 2010