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 A027180 #15 Oct 24 2019 19:14:22
%S A027180 1,7,27,79,199,459,1003,2119,4383,8947,18115,36495,73303,146971,
%T A027180 294363,589207,1178959,2358531,4717747,9436255,18873351,37747627,
%U A027180 75496267,150993639,301988479,603978259,1207957923,2415917359,4831836343,9663674427,19327350715
%N A027180 a(n) = Sum_{0<=j<=i<=n} A027170(i, j).
%H A027180 Colin Barker, <a href="/A027180/b027180.txt">Table of n, a(n) for n = 0..1000</a>
%H A027180 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (5,-9,7,-2).
%F A027180 a(n) = 18*2^n - 2*n^2 - 10*n - 17.
%F A027180 From _Colin Barker_, Feb 20 2016: (Start)
%F A027180 a(n) = 5*a(n-1)-9*a(n-2)+7*a(n-3)-2*a(n-4) for n>3.
%F A027180 G.f.: (1+x)^2 / ((1-x)^3*(1-2*x)).
%F A027180 (End)
%t A027180 LinearRecurrence[{5,-9,7,-2},{1,7,27,79},50] (* _Harvey P. Dale_, Jul 08 2019 *)
%o A027180 (PARI) Vec((1+x)^2/((1-x)^3*(1-2*x)) + O(x^40)) \\ _Colin Barker_, Feb 20 2016
%Y A027180 Partial sums of A027178.
%K A027180 nonn,easy
%O A027180 0,2
%A A027180 _Clark Kimberling_