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 A110488 #14 Sep 05 2024 08:09:24 %S A110488 1,1,1,2,2,1,5,5,3,1,14,14,10,4,1,42,42,35,17,5,1,132,132,126,74,26,6, %T A110488 1,429,429,462,326,137,37,7,1,1430,1430,1716,1446,726,230,50,8,1,4862, %U A110488 4862,6435,6441,3858,1434,359,65,9,1,16796,16796,24310,28770,20532,8952,2582,530,82,10,1 %N A110488 A number triangle based on the Catalan numbers. %C A110488 Columns include A000108, A001700, A049027(n+1), A076025(n+1). Rows sums are A110489, diagonal sums are A110490. %H A110488 G. C. Greubel, <a href="/A110488/b110488.txt">Table of n, a(n) for the first 50 rows, flattened</a> %F A110488 T(n, k) = Sum_{j=0..(n-k)} 2*(j+1)*(k-1)^j*C(2*(n-k)+1, n-k-j)/(n-k+j+2). %F A110488 Column k has g.f. x^k*c(x)/(1-k*x*c(x)) where c(x) is the g.f. of A000108. %F A110488 T(n,0) = Catalan(n), T(n,1) = Catalan(n), T(n,n) = 1. - _G. C. Greubel_, Aug 28 2017 %e A110488 Rows begin %e A110488 1; %e A110488 1, 1; %e A110488 2, 2, 1; %e A110488 5, 5, 3, 1; %e A110488 14, 14, 10, 4, 1; %e A110488 42, 42, 35, 17, 5, 1; %t A110488 T[n_, 0] := CatalanNumber[n]; T[n_, 1] := CatalanNumber[n]; T[n_, n_] := 1; T[n_, k_] := Sum[2*(j + 1)*(k - 1)^j*Binomial[2 (n - k) + 1, n - k - j]/(n - k + j + 2), {j, 0, n - k}]; Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* _G. C. Greubel_, Aug 28 2017 *) %K A110488 easy,nonn,tabl %O A110488 0,4 %A A110488 _Paul Barry_, Jul 22 2005