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 A208518 #12 Mar 30 2012 18:58:13 %S A208518 1,1,1,1,3,2,1,6,7,3,1,10,16,14,5,1,15,30,40,28,8,1,21,50,90,93,53,13, %T A208518 1,28,77,175,238,203,99,21,1,36,112,308,518,588,428,181,34,1,45,156, %U A208518 504,1008,1428,1380,873,327,55,1,55,210,780,1806,3066,3690,3105 %N A208518 Triangle of coefficients of polynomials u(n,x) jointly generated with A208519; see the Formula section. %C A208518 coefficient of x^(n-1): = Fibonacci(n) = A000045(n) %C A208518 col 1: A000012 %C A208518 col 2: A000217 (triangular numbers) %C A208518 col 3: A005581 %C A208518 col 4: A117662 %C A208518 alternating row sums: signed version of (-1+Fibonacci(n)) %F A208518 u(n,x)=u(n-1,x)+x*v(n-1,x), %F A208518 v(n,x)=x*u(n-1,x)+(x+1)*v(n-1,x)+1, %F A208518 where u(1,x)=1, v(1,x)=1. %e A208518 First five rows: %e A208518 1 %e A208518 1...1 %e A208518 1...3....2 %e A208518 1...6....7....3 %e A208518 1...10...16...14...5 %e A208518 First five polynomials u(n,x): %e A208518 1 %e A208518 1 + x %e A208518 1 + 3x + 2x^2 %e A208518 1 + 6x + 7x^2 + 3x^3 %e A208518 1 + 10x + 16x^2 + 14x^3 + 5x^4 %t A208518 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A208518 u[n_, x_] := u[n - 1, x] + x*v[n - 1, x]; %t A208518 v[n_, x_] := x*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A208518 Table[Expand[u[n, x]], {n, 1, z/2}] %t A208518 Table[Expand[v[n, x]], {n, 1, z/2}] %t A208518 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A208518 TableForm[cu] %t A208518 Flatten[%] (* A208518 *) %t A208518 Table[Expand[v[n, x]], {n, 1, z}] %t A208518 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A208518 TableForm[cv] %t A208518 Flatten[%] (* A208519 *) %Y A208518 Cf. A208519. %K A208518 nonn,tabl %O A208518 1,5 %A A208518 _Clark Kimberling_, Feb 28 2012