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 A349727 #17 Jul 31 2023 21:31:24 %S A349727 1,0,1,1,1,1,4,3,2,1,15,10,6,3,1,56,35,20,10,4,1,210,126,70,35,15,5,1, %T A349727 792,462,252,126,56,21,6,1,3003,1716,924,462,210,84,28,7,1,11440,6435, %U A349727 3432,1716,792,330,120,36,8,1,43758,24310,12870,6435,3003,1287,495,165,45,9,1 %N A349727 Triangle read by rows, T(n, k) = [x^(n - k)] hypergeom([-n, -1 + n], [-n], x). %e A349727 Triangle starts: %e A349727 [0] 1; %e A349727 [1] 0, 1; %e A349727 [2] 1, 1, 1; %e A349727 [3] 4, 3, 2, 1; %e A349727 [4] 15, 10, 6, 3, 1; %e A349727 [5] 56, 35, 20, 10, 4, 1; %e A349727 [6] 210, 126, 70, 35, 15, 5, 1; %e A349727 [7] 792, 462, 252, 126, 56, 21, 6, 1; %e A349727 [8] 3003, 1716, 924, 462, 210, 84, 28, 7, 1; %e A349727 [9] 11440, 6435, 3432, 1716, 792, 330, 120, 36, 8, 1; %p A349727 p := n -> hypergeom([-n, -1 + n], [-n], x): %p A349727 seq(seq(coeff(simplify(p(n)), x, n - k), k = 0..n), n = 0..10); %t A349727 (* rows[0..k], k[0..oo] *) %t A349727 r={};k=11;For[n=0,n<k+1,n++,AppendTo[r,Binomial[2*k-2-n,k-2]]];r %t A349727 (* columns [0..n], n[0..oo] *) %t A349727 c={};n=0;For[k=n,k<n+13,k++,AppendTo[c,Binomial[2*k-2-n,k-2]]];c %t A349727 (* sequence *) %t A349727 s={};For[k=0,k<13,k++,For[n=0,n<k+1,n++,AppendTo[s,Binomial[2*k-2-n,k-2]]]];s (* _Detlef Meya_, Jun 26 2023 *) %Y A349727 Row sums: A088218, alternating row sums: A091526. %Y A349727 Central coefficients: binomial(3*n-2, n) (cf. A117671). %Y A349727 T(n, 0) = binomial(2*(n-1), n) (cf. A001791). %Y A349727 Cf. A257635. %K A349727 nonn,tabl %O A349727 0,7 %A A349727 _Peter Luschny_, Nov 27 2021