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 A123235 #15 Nov 23 2019 21:09:29 %S A123235 1,1,1,2,1,8,3,-1,48,16,-7,384,120,-59,1,3840,1152,-606,17,46080, %T A123235 13440,-7392,263,-1,645120,184320,-104640,4288,-31,10321920,2903040, %U A123235 -1687680,76000,-759,1,185794560,51609600,-30562560,1472640,-17950,49 %N A123235 Triangle of coefficients p(k, x), where p(k, x) = 2*(k-1)*p(k-1, x) -x*p(k-2, x), read by rows. %C A123235 Row sums give A093856. %D A123235 Eugene Jahnke and Fritz Emde, Table of Functions with Formulae and Curves, Dover Book, New York, 1945, page 144. %H A123235 G. C. Greubel, <a href="/A123235/b123235.txt">Rows n = 0..30 of triangle, flattened</a> %F A123235 Coefficient list of the polynomials p(k, x) = 2*(k-1)*p(k-1, x) - x*p(k - 2, x), with p(0, x) = 1 and p(1, x) = 1 + x. %e A123235 Triangle begins as: %e A123235 1; %e A123235 1, 1; %e A123235 2, 1; %e A123235 8, 3, -1; %e A123235 48, 16, -7; %e A123235 384, 120, -59, 1; %e A123235 3840, 1152, -606, 17; %e A123235 46080, 13440, -7392, 263, -1; %t A123235 p[n_, x_]:= p[n, x]= If[n==0, 1, If[n==1, x+1, 2*(n-1)*p[n-1, x] -x*p[n-2, x]]]; Table[CoefficientList[p[n, x], x], {n, 0, 10}]//Flatten %Y A123235 Cf. A093856. %K A123235 tabf,sign %O A123235 0,4 %A A123235 _Roger L. Bagula_, Oct 06 2006 %E A123235 Edited by _G. C. Greubel_, Nov 22 2019