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 A210204 #6 Jan 14 2022 21:25:09 %S A210204 1,3,2,7,8,2,15,24,12,2,31,64,48,16,2,63,160,160,80,20,2,127,384,480, %T A210204 320,120,24,2,255,896,1344,1120,560,168,28,2,511,2048,3584,3584,2240, %U A210204 896,224,32,2,1023,4608,9216,10752,8064,4032,1344,288,36,2,2047 %N A210204 Triangle of coefficients of polynomials v(n,x) jointly generated with A210203; see the Formula section. %C A210204 Column 1: -1+2^n. %C A210204 Row sums: A048473. %C A210204 Alternating row sums: 1,1,1,1,1,1,1,1,1,... %C A210204 For a discussion and guide to related arrays, see A208510. %C A210204 Row sums without first column give A056182. - _Alois P. Heinz_, Jan 14 2022 %F A210204 u(n,x)=u(n-1,x)+v(n-1,x)+1, %F A210204 v(n,x)=(x+1)*u(n-1,x)+(x+1)*v(n-1,x)+1, %F A210204 where u(1,x)=1, v(1,x)=1. %e A210204 First five rows: %e A210204 1 %e A210204 3....2 %e A210204 7....8....2 %e A210204 15...24...12...2 %e A210204 31...64...48...16...2 %e A210204 First three polynomials v(n,x): 1, 3 + 2x , 7 + 8x + 2x^2. %t A210204 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210204 u[n_, x_] := u[n - 1, x] + v[n - 1, x] + 1; %t A210204 v[n_, x_] := (x + 1)*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A210204 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210204 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210204 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210204 TableForm[cu] %t A210204 Flatten[%] (* A210203 *) %t A210204 Table[Expand[v[n, x]], {n, 1, z}] %t A210204 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210204 TableForm[cv] %t A210204 Flatten[%] (* A210204 *) %Y A210204 Cf. A210203, A208510. %Y A210204 Cf. A056182. %K A210204 nonn,tabl %O A210204 1,2 %A A210204 _Clark Kimberling_, Mar 18 2012