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 A132787 #6 Aug 10 2018 17:37:56 %S A132787 1,1,1,1,5,1,1,11,11,1,1,19,39,19,1,1,29,99,99,29,1,1,41,209,349,209, %T A132787 41,1,1,55,391,979,979,391,55,1,1,71,671,2351,3527,2351,671,71,1,1,89, %U A132787 1079,5039,10583,10583,5039,1079,89,1,1,109,1649,9899,27719,38807,27719,9899,1649,109,1 %N A132787 Triangle read by rows: T(n,k) = 2*A001263(n,k) - 1. %H A132787 Andrew Howroyd, <a href="/A132787/b132787.txt">Table of n, a(n) for n = 1..1275</a> (rows 1..50) %F A132787 Equals 2*A001263 - A000012 as infinite lower triangular matrices; where A001263 = the Narayana triangle. %F A132787 T(n,k) = 2*binomial(n-1, k-1) * binomial(n, k-1) / k - 1. - _Andrew Howroyd_, Aug 10 2018 %e A132787 First few rows of the triangle are: %e A132787 1; %e A132787 1, 1; %e A132787 1, 5, 1; %e A132787 1, 11, 11, 1; %e A132787 1, 19, 39, 19, 1; %e A132787 1, 29, 99, 99, 29, 1; %e A132787 ... %o A132787 (PARI) T(n,k) = if(k<=n, 2*binomial(n-1, k-1) * binomial(n, k-1) / k - 1, 0); \\ _Andrew Howroyd_, Aug 10 2018 %Y A132787 Column 2 is A018387. %Y A132787 Row sums are A132788. %Y A132787 Cf. A001263. %K A132787 nonn,tabl %O A132787 1,5 %A A132787 _Gary W. Adamson_, Aug 30 2007 %E A132787 a(20) corrected and terms a(56) and beyond from _Andrew Howroyd_, Aug 10 2018