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 A298213 #5 Jan 18 2018 17:43:17 %S A298213 1,0,1,0,2,1,0,5,6,1,0,12,32,12,1,0,41,160,110,20,1,0,142,856,900,280, %T A298213 30,1,0,685,4816,7231,3360,595,42,1,0,3192,29952,58632,37856,9800, %U A298213 1120,56,1,0,19921,199680,493100,416640,147126,24192,1932,72,1 %N A298213 Triangle read by rows, expansion of exp(x*exp(z)*tan(z)). %e A298213 Triangle starts: %e A298213 0: 1; %e A298213 1: 0, 1; %e A298213 2: 0, 2, 1; %e A298213 3: 0, 5, 6, 1; %e A298213 4: 0, 12, 32, 12, 1; %e A298213 5: 0, 41, 160, 110, 20, 1; %e A298213 6: 0, 142, 856, 900, 280, 30, 1; %e A298213 7: 0, 685, 4816, 7231, 3360, 595, 42, 1; %e A298213 8: 0, 3192, 29952, 58632, 37856, 9800, 1120, 56, 1; %p A298213 gf := exp(x*exp(z)*tan(z)): %p A298213 X := n -> series(gf, z, n+2): %p A298213 Z := n -> n!*expand(simplify(coeff(X(n), z, n))): %p A298213 A298213_row := n -> op(PolynomialTools:-CoefficientList(Z(n), x)): %p A298213 seq(A298213_row(n), n=0..8); %Y A298213 T(n,1) = A009739(n), T(n,n) = A002378(n-1). %Y A298213 Row sums are A009248. %Y A298213 Cf. A075497. %K A298213 nonn,tabl %O A298213 0,5 %A A298213 _Peter Luschny_, Jan 15 2018