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 A028358 #18 Jul 08 2025 18:32:26
%S A028358 1,4,10,20,33,48,64,82,103,128,156,186,217,250,286,326,369,414,460,
%T A028358 508,559,614,672,732,793,856,922,992,1065,1140,1216,1294,1375,1460,
%U A028358 1548,1638,1729,1822,1918,2018,2121
%N A028358 Partial sums of A028357.
%H A028358 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,0,3,-3,1).
%F A028358 G.f.: ( -1-x-x^2-2*x^3 ) / ( (1+x)*(x^2-x+1)*(x-1)^3 ). - _R. J. Mathar_, Dec 15 2015
%F A028358 a(n) = (9 + 72*n + 30*n^2 + 32*cos((n + 1)*Pi/3) - (-1)^n)/24. - _Greg Dresden_, Jun 22 2021
%t A028358 LinearRecurrence[{3,-3,0,3,-3,1},{1,4,10,20,33,48},50] (* _Harvey P. Dale_, Jun 14 2021 *)
%t A028358 Table[(9 + 72n + 30n^2 + 32Cos[(n + 1)Pi/3] - (-1)^n)/24, {n, 0, 40}] (* _Greg Dresden_, Jun 22 2021 *)
%K A028358 nonn,easy
%O A028358 0,2
%A A028358 _N. J. A. Sloane_