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 A381883 #10 Apr 03 2025 09:58:47 %S A381883 1,1,1,1,3,3,1,5,10,10,1,7,21,35,35,1,9,36,84,126,126,1,11,55,165,330, %T A381883 462,462,1,13,78,286,715,1287,1716,1716,1,15,105,455,1365,3003,5005, %U A381883 6435,6435,1,17,136,680,2380,6188,12376,19448,24310,24310 %N A381883 Triangle read by rows: T(n, k) = binomial(2*n - 1, k). %e A381883 Triangle starts: %e A381883 [0] 1; %e A381883 [1] 1, 1; %e A381883 [2] 1, 3, 3; %e A381883 [3] 1, 5, 10, 10; %e A381883 [4] 1, 7, 21, 35, 35; %e A381883 [5] 1, 9, 36, 84, 126, 126; %e A381883 [6] 1, 11, 55, 165, 330, 462, 462; %e A381883 [7] 1, 13, 78, 286, 715, 1287, 1716, 1716; %e A381883 [8] 1, 15, 105, 455, 1365, 3003, 5005, 6435, 6435; %p A381883 T := (n, k) -> binomial(2*n - 1, k): %p A381883 seq(seq(T(n, k), k = 0..n), n = 0..9); %t A381883 T[n_,k_]:=Binomial[2n-1,k];Table[T[n,k],{n,0,9},{k,0,n}]//Flatten (* _James C. McMahon_, Apr 02 2025 *) %Y A381883 Cf. A007318 (Pascal), A088218 (main diagonal), A114121 (row sums), A262977 (central terms). %K A381883 nonn,tabl,easy %O A381883 0,5 %A A381883 _Peter Luschny_, Mar 15 2025