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 A343171 #17 Apr 21 2021 23:52:28 %S A343171 1,1,3,1,11,5,57,38,5,361,302,61,2763,2827,845,61,24611,29607,11421, %T A343171 1385,250737,347372,165678,30108,1385,2873041,4501564,2551326,610444, %U A343171 50521,36581523,63967093,42044902,12558738,1578727,50521 %N A343171 Irregular triangle read by rows: coefficients of polynomials xi_n. %H A343171 Shi-Mei Ma, Qi Fang, Toufik Mansour, and Yeong-Nan Yeh, <a href="https://arxiv.org/abs/2104.09374">Alternating Eulerian polynomials and left peak polynomials</a>, arXiv:2104.09374 [math.CO], 2021. %e A343171 Triangle begins: %e A343171 1; %e A343171 1; %e A343171 3, 1; %e A343171 11, 5; %e A343171 57, 38, 5; %e A343171 361, 302, 61; %e A343171 ... %t A343171 xi[0][_] = 1; %t A343171 xi[n_][x_] := xi[n, x] = (2n - 1 + (n-1) x) xi[n-1][x] - (1 + x)(4 + 2x)* xi[n-1]'[x]; %t A343171 Table[CoefficientList[xi[n][x], x], {n, 0, 10}] // Flatten (* _Jean-François Alcover_, Apr 21 2021 *) %Y A343171 First column gives A001586. %Y A343171 Cf. A343170. %K A343171 nonn,tabf %O A343171 0,3 %A A343171 _N. J. A. Sloane_, Apr 21 2021 %E A343171 More terms from _Jean-François Alcover_, Apr 21 2021