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 A155586 #10 Aug 04 2020 01:40:01 %S A155586 1,1,1,1,1,1,1,2,1,1,1,5,2,1,1,1,14,5,2,1,1,1,42,14,5,2,1,1,1,132,42, %T A155586 14,5,2,1,1,1,429,132,42,14,5,2,1,1,1,1430,429,132,42,14,5,2,1,1,1, %U A155586 4862,1430,429,132,42,14,5,2,1,1,1,16796,4862,1430,429,132,42,14,5,2,1,1 %N A155586 A modified Catalan sequence array. %C A155586 Row sums are in A155587. Stieltjes associate array to A091491. %F A155586 T(n,k) = [k <= n] * if(k=0, 1, A000108(n-k)) for 0 <= k <= n, where [ ] is the Iverson bracket. %F A155586 Bivariate o.g.f.: 1/(1 - x) + c(x) * x*y/(1 - x*y), where c(x) is the o.g.f. of A000108. - _Petros Hadjicostas_, Aug 03 2020 %e A155586 Triangle T(n,k) (with rows n >= 0 and columns k = 0..n) begins %e A155586 1; %e A155586 1, 1; %e A155586 1, 1, 1; %e A155586 1, 2, 1, 1; %e A155586 1, 5, 2, 1, 1; %e A155586 1, 14, 5, 2, 1, 1; %e A155586 1, 42, 14, 5, 2, 1, 1; %e A155586 1, 132, 42, 14, 5, 2, 1, 1; %e A155586 1, 429, 132, 42, 14, 5, 2, 1, 1; %e A155586 1, 1430, 429, 132, 42, 14, 5, 2, 1, 1; %e A155586 ... %Y A155586 Cf. A000108, A091491, A155587. %K A155586 easy,nonn,tabl %O A155586 0,8 %A A155586 _Paul Barry_, Jan 24 2009