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 A155917 #4 Jun 02 2025 01:19:47 %S A155917 -3,-2,-2,0,240,0,3360,3360,-5,30380,105570,30380,-5,-18,232710, %T A155917 2032620,2032620,232710,-18,-42,1637748,31186890,74043480,31186890, %U A155917 1637748,-42,-80,10932880,420179760,1990483600,1990483600,420179760,10932880,-80 %N A155917 A difference triangle of Pascal-Sierpinski 5th level and the Pascal second derivative: a(n,k)= (4*n - 4*k + 1)a(n - 1, k - 1) + (4*k - 3)a(n - 1, k); p(x,n)=(Sum[10*n*(n - 1)*a(n, k)*x^(k - 1) - D[(x + 1)^(n + 2), {x, 2}]/(x + 1), {k, n}])/2. %C A155917 Row sums are: %F A155917 a(n,k)= (4*n - 4*k + 1)a(n - 1, k - 1) + (4*k - 3)a(n - 1, k); %F A155917 p(x,n)=(Sum[10*n*(n - 1)*a(n, k)*x^(k - 1) - D[(x + 1)^(n + 2), {x, 2}]/(x + 1), {k, n}])/2; %F A155917 t(n,m)=coefficients(p(x,n)). %e A155917 {-3}, %e A155917 {-2, -2}, %e A155917 {0, 240}, %e A155917 {0, 3360, 3360}, %e A155917 {-5, 30380, 105570, 30380, -5}, %e A155917 {-18, 232710, 2032620, 2032620, 232710, -18}, %e A155917 {-42, 1637748, 31186890, 74043480, 31186890, 1637748, -42}, %e A155917 {-80, 10932880, 420179760, 1990483600, 1990483600, 420179760, 10932880, -80}, %e A155917 {-135, 70305480, 5213648700, 44614752120, 87013084950, 44614752120, 5213648700, 70305480, -135}, %e A155917 {-210, 439442910, 61202397240, 887917071960, 3020166679140, 3020166679140, 887917071960, 61202397240, 439442910, -210} %t A155917 A[n_, 1] := 1; A[n_, n_] := 1; %t A155917 A[n_, k_] := (4*n - 4*k + 1)A[n - 1, k - 1] + (4*k - 3)A[n - 1, k]; %t A155917 a = Table[ExpandAll[(Sum[10*n*(n - 1)*A[n, k]*x^(k - 1) - D[(x + 1)^(n + 2), {x, 2}]/(x + 1), {k, n}])/2], {n, 10}]; %t A155917 Table[CoefficientList[ExpandAll[a[[n]]], x], {n, 1, Length[a]}]; %t A155917 Flatten[%] %Y A155917 A142459 %K A155917 sign,tabl,uned %O A155917 1,1 %A A155917 _Roger L. Bagula_, Jan 30 2009