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 A247492 #15 Oct 23 2021 10:54:56 %S A247492 1,-1,2,1,0,3,-1,0,2,4,1,0,0,5,5,-1,0,0,2,9,6,1,0,0,0,7,14,7,-1,0,0,0, %T A247492 2,16,20,8,1,0,0,0,0,9,30,27,9,-1,0,0,0,0,2,25,50,35,10,1,0,0,0,0,0, %U A247492 11,55,77,44,11,-1,0,0,0,0,0,2,36,105,112,54,12 %N A247492 Triangle read by rows: T(n, k) = binomial(k-1, n-k)*(n+1)/(n+1-k), 0 <= k <= n. %F A247492 Sum_{k = 0..n} T(n, k) = A001350(n+1). %F A247492 G.f.: (x^2*y + 1)/((x^4 + 2*x^3 + x^2)*y^2 + (-x^3 - 3*x^2 - 2*x)*y + x + 1). Or: (x^2*y + 1)/((x + 1)*(x*y - 1)*(x^2*y + x*y - 1)). - _Vladimir Kruchinin_, Oct 23 2021 %e A247492 [0] 1; %e A247492 [1] -1, 2; %e A247492 [2] 1, 0, 3; %e A247492 [3] -1, 0, 2, 4; %e A247492 [4] 1, 0, 0, 5, 5; %e A247492 [5] -1, 0, 0, 2, 9, 6; %e A247492 [6] 1, 0, 0, 0, 7, 14, 7; %e A247492 . %e A247492 Taylor series: 1 + x*(2*y - 1) + x^2*(3*y^2 + 1) + x^3*(4*y^3 + 2*y^2 - 1) + x^4*(5*y^4 + 5*y^3 + 1) + O(x^5). %p A247492 T := (n, k) -> (n+1)*binomial(k-1, n-k)/(n+1-k); %p A247492 for n from 0 to 11 do seq(T(n,k), k=0..n) od; %Y A247492 Cf. A001350 (row sums), A098599, A100218. %K A247492 sign,tabl %O A247492 0,3 %A A247492 _Peter Luschny_, Oct 01 2014