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 A091698 #17 Nov 05 2020 14:29:19 %S A091698 1,-1,1,1,-3,1,-1,8,-5,1,1,-23,19,-7,1,-1,74,-69,34,-9,1,1,-262,256, %T A091698 -147,53,-11,1,-1,993,-986,615,-265,76,-13,1,1,-3943,3935,-2571,1235, %U A091698 -431,103,-15,1,-1,16178,-16169,10862,-5591,2216,-653,134,-17,1,1 %N A091698 Matrix inverse of triangle A063967. %C A091698 Riordan array (1/(1+x), (sqrt(1+6x+5x^2)-x-1)/(2(1+x))). The absolute value array is (1/(1-x),xc(x)/(1-xc(x))) where c(x) is the g.f. of A000108. It factorizes as (1/(1-x),x/(1-x))(1,xc(x)). - _Paul Barry_, Jun 10 2005 %H A091698 Lara K. Pudwell, <a href="http://arxiv.org/abs/1408.6823">Ascent sequences and the binomial convolution of Catalan numbers</a>, arXiv preprint arXiv:1408.6823 [math.CO], 2014. %e A091698 From _Paul Barry_, Apr 15 2010: (Start) %e A091698 Triangle begins %e A091698 1, %e A091698 -1, 1, %e A091698 1, -3, 1, %e A091698 -1, 8, -5, 1, %e A091698 1, -23, 19, -7, 1, %e A091698 -1, 74, -69, 34, -9, 1, %e A091698 1, -262, 256, -147, 53, -11, 1, %e A091698 -1, 993, -986, 615, -265, 76, -13, 1, %e A091698 1, -3943, 3935, -2571, 1235, -431, 103, -15, 1 %e A091698 Production matrix begins %e A091698 -1, 1, %e A091698 0, -2, 1, %e A091698 0, 1, -2, 1, %e A091698 0, -1, 1, -2, 1, %e A091698 0, 1, -1, 1, -2, 1, %e A091698 0, -1, 1, -1, 1, -2, 1, %e A091698 0, 1, -1, 1, -1, 1, -2, 1, %e A091698 0, -1, 1, -1, 1, -1, 1, -2, 1, %e A091698 0, 1, -1, 1, -1, 1, -1, 1, -2, 1, %e A091698 0, -1, 1, -1, 1, -1, 1, -1, 1, -2, 1 (End) %t A091698 rows = 11; t[n_, k_] := Sum[Binomial[j, n - j]*Binomial[j, k], {j, 0, n}]; T = Table[t[n, k], {n, 0, rows - 1}, {k, 0, rows - 1}] // Inverse; Table[ T[[n, k]], {n, 1, rows}, {k, 1, n}] // Flatten (* _Jean-François Alcover_, Oct 11 2017 *) %Y A091698 Row sums: A091699. Row sums (absolute values): A007317. Column 1: A050511. %K A091698 sign,tabl %O A091698 0,5 %A A091698 _Christian G. Bower_, Jan 29 2004