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 A208512 #5 Mar 30 2012 18:58:13 %S A208512 1,2,2,2,5,4,2,7,12,8,2,9,21,28,16,2,11,32,58,64,32,2,13,45,101,152, %T A208512 144,64,2,15,60,159,296,384,320,128,2,17,77,234,513,824,944,704,256,2, %U A208512 19,96,328,822,1554,2208,2272,1536,512,2,21,117,443,1244,2685 %N A208512 Triangle of coefficients of polynomials v(n,x) jointly generated with A208511; see the Formula section. %C A208512 Alternating row sums are signed Fibonacci numbers (A000045). %F A208512 u(n,x)=u(n-1,x)+x*v(n-1,x), %F A208512 v(n,x)=u(n-1,x)+2x*v(n-1,x)+1, %F A208512 where u(1,x)=1, v(1,x)=1. %e A208512 First five rows: %e A208512 1 %e A208512 2...2 %e A208512 2...5...4 %e A208512 2...7...12...8 %e A208512 2...9...21...28...16 %e A208512 First five polynomials v(n,x): %e A208512 1 %e A208512 2 + 2x %e A208512 2 + 5x + 4x^2 %e A208512 2 + 7x + 12x^2 + 8x^3 %e A208512 2 + 9x + 21x^2 + 28x^3 + 16x^4 %t A208512 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A208512 u[n_, x_] := u[n - 1, x] + x*v[n - 1, x]; %t A208512 v[n_, x_] := u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A208512 Table[Expand[u[n, x]], {n, 1, z/2}] %t A208512 Table[Expand[v[n, x]], {n, 1, z/2}] %t A208512 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A208512 TableForm[cu] %t A208512 Flatten[%] (* A208511 *) %t A208512 Table[Expand[v[n, x]], {n, 1, z}] %t A208512 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A208512 TableForm[cv] %t A208512 Flatten[%] (* A208512 *) %Y A208512 Cf. A208511. %K A208512 nonn,tabl %O A208512 1,2 %A A208512 _Clark Kimberling_, Feb 28 2012