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 A102713 #10 Jan 08 2020 09:44:01
%S A102713 1,2,8,18,48,110,260,586,1320,2918,6412,13954,30192,64926,138964,
%T A102713 296122,628664,1330134,2805916,5903090,12388736,25942542,54215268,
%U A102713 113090858,235502408,489646150,1016575020,2107715426,4364561680,9027384958,18651293172,38495632794
%N A102713 Total sum of odd parts in all compositions of n.
%H A102713 Andrew Howroyd, <a href="/A102713/b102713.txt">Table of n, a(n) for n = 1..1000</a>
%H A102713 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,3,-4,-4).
%F A102713 a(n) = ((15*n+4)*2^(n-1)-2*(3*n+1)*(-1)^n)/27.
%F A102713 From _Colin Barker_, Jan 08 2020: (Start)
%F A102713 G.f.: x*(1 + x^2) / ((1 + x)^2*(1 - 2*x)^2).
%F A102713 a(n) = 2*a(n-1) + 3*a(n-2) - 4*a(n-3) - 4*a(n-4) for n>4.
%F A102713 (End)
%o A102713 (PARI) a(n)={((15*n+4)*2^(n-1) - 2*(3*n+1)*(-1)^n)/27} \\ _Andrew Howroyd_, Jan 08 2020
%o A102713 (PARI) Vec(x*(1 + x^2) / ((1 + x)^2*(1 - 2*x)^2) + O(x^35)) \\ _Colin Barker_, Jan 08 2020
%Y A102713 Cf. A066967, A073371.
%K A102713 easy,nonn
%O A102713 1,2
%A A102713 _Vladeta Jovovic_, Feb 06 2005
%E A102713 Terms a(26) and beyond from _Andrew Howroyd_, Jan 08 2020