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 A261054 #7 Aug 10 2024 15:47:50
%S A261054 2,7,20,51,118,260,548,1121,2236,4373,8412,15960,29926,55547,102196,
%T A261054 186567,338258,609532,1092328,1947829,3457724,6112873,10766328,
%U A261054 18896880,33062090,57675631,100338836,174117915,301432558,520686644,897559340,1544207369,2651881468,4546263293,7781245524
%N A261054 Expansion of ( 2+x-x^2+x^3 ) / (1-x^2-x)^3 .
%C A261054 Third column of A234713.
%H A261054 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (3,0,-5,0,3,1).
%F A261054 a(n) = 2*A001628(n) +A001628(n-1) -A001628(n-2) +A001628(n-3).
%t A261054 LinearRecurrence[{3,0,-5,0,3,1},{2,7,20,51,118,260},40] (* _Harvey P. Dale_, Aug 10 2024 *)
%Y A261054 Cf. A234713.
%K A261054 nonn,easy
%O A261054 0,1
%A A261054 _R. J. Mathar_, Aug 08 2015