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 A281862 #7 Feb 18 2017 21:53:17
%S A281862 0,1,3,4,1,-6,-11,-6,9,21,14,-12,-34,-25,15,50,39,-18,-69,-56,21,91,
%T A281862 76,-24,-116,-99,27,144,125,-30,-175,-154,33,209,186,-36,-246,-221,39,
%U A281862 286,259,-42,-329,-300,45,375
%N A281862 Riordan transform of the triangular number sequence A000217 with the Chebyshev S matrix A049310.
%C A281862 For the analogous sequence with the inverse S Riordan matrix A053121 see A189391.
%F A281862 a(n) = Sum_{m=0..n} A049310(n,m)*A000217(m), n >= 0.
%F A281862 a(n) = b(n-1) + b(n-3), n >= 0 with b(-3) = b(-2) = b(-1) = 0 and b(n) = A128504(n) for n >= 0.
%F A281862 G.f.: (1/(1+x^2))*Tri(x/(1+x^2)), with Tri(x) = x/(1-x)^3 (g.f. of A000217).
%F A281862 G.f. x*(1 + x^2)/(1 - x + x^2)^3.
%t A281862 CoefficientList[Series[x (1 + x^2)/(1 - x + x^2)^3, {x, 0, 45}], x] (* _Michael De Vlieger_, Feb 18 2017 *)
%Y A281862 Cf. A000217, A049310, A128504, A189391.
%K A281862 sign,easy
%O A281862 0,3
%A A281862 _Wolfdieter Lang_, Feb 18 2017