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 A126030 #6 Jul 03 2020 14:55:05 %S A126030 1,0,1,0,0,1,-1,0,0,1,0,-2,0,0,1,0,0,-3,0,0,1,1,0,0,-4,0,0,1,0,3,0,0, %T A126030 -5,0,0,1,0,0,6,0,0,-6,0,0,1,-1,0,0,10,0,0,-7,0,0,1,0,-4,0,0,15,0,0 %N A126030 Riordan array (1/(1+x^3),x/(1+x^3)). %C A126030 Inverse is A111373. Row sums are A050935(n+2). Diagonal sums are an alternating sign version of A000931(n+3) with g.f. 1/(1-x^2+x^3). %H A126030 Milan Janjic, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL19/Janjic/janjic73.html">Binomial Coefficients and Enumeration of Restricted Words</a>, Journal of Integer Sequences, 2016, Vol 19, #16.7.3 %F A126030 Number triangle T(n,k)=C(k+(n-k)/3,(n-k)/3)*(-1)^(n-k)*(2*cos(2*pi*(n-k)/3)+1)/3 %e A126030 Triangle begins %e A126030 .1, %e A126030 .0, 1, %e A126030 .0, 0, 1, %e A126030 .-1, 0, 0, 1, %e A126030 .0, -2, 0, 0, 1, %e A126030 .0, 0, -3, 0, 0, 1, %e A126030 .1, 0, 0, -4, 0, 0, 1, %e A126030 .0, 3, 0, 0, -5, 0, 0, 1, %e A126030 .0, 0, 6, 0, 0, -6, 0, 0, 1, %e A126030 .-1, 0, 0, 10, 0, 0, -7, 0, 0, 1, %e A126030 .0, -4, 0, 0, 15, 0, 0, -8, 0, 0, 1 %K A126030 easy,sign,tabl %O A126030 0,12 %A A126030 _Paul Barry_, Dec 15 2006