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 A210195 #4 Mar 30 2012 18:58:16 %S A210195 1,3,5,4,7,12,8,9,24,32,16,11,40,80,80,32,13,60,160,240,192,64,15,84, %T A210195 280,560,672,448,128,17,112,448,1120,1792,1792,1024,256,19,144,672, %U A210195 2016,4032,5376,4608,2304,512,21,180,960,3360,8064,13440,15360 %N A210195 Triangle of coefficients of polynomials u(n,x) jointly generated with A210196; see the Formula section. %C A210195 Row sums: powers of 3 %C A210195 Periodic alternating row sums: 1,3,1,3,1,3,1,3,... %C A210195 For a discussion and guide to related arrays, see A208510. %F A210195 u(n,x)=u(n-1,x)+v(n-1,x)+1, %F A210195 v(n,x)=2x*u(n-1,x)+2x*v(n-1,x)+1, %F A210195 where u(1,x)=1, v(1,x)=1. %e A210195 First five rows: %e A210195 1 %e A210195 3 %e A210195 5...4 %e A210195 7...12...8 %e A210195 9...24...32...16 %e A210195 First three polynomials u(n,x): 1, 3, 5 + 4x. %t A210195 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210195 u[n_, x_] := u[n - 1, x] + v[n - 1, x] + 1; %t A210195 v[n_, x_] := 2 x*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A210195 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210195 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210195 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210195 TableForm[cu] %t A210195 Flatten[%] (* A210195 *) %t A210195 Table[Expand[v[n, x]], {n, 1, z}] %t A210195 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210195 TableForm[cv] %t A210195 Flatten[%] (* A210196 *) %Y A210195 Cf. A210196, A208510. %K A210195 nonn,tabf %O A210195 1,2 %A A210195 _Clark Kimberling_, Mar 18 2012