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 A123552 #49 Oct 16 2017 02:03:33
%S A123552 1,1,1,2,3,3,4,6,7,8,11,14,16,20,26,31,37,47,58,69,85,106,128,155,192,
%T A123552 235,284,348,428,520,633,777,949,1154,1411,1727,2104,2566,3139,3832,
%U A123552 4671,5706,6972,8504,10378,12679,15477,18883,23058,28157,34361,41942,51216,62519
%N A123552 Expansion of 1/(1 - x - x^3 + x^5).
%H A123552 G. C. Greubel, <a href="/A123552/b123552.txt">Table of n, a(n) for n = 0..1000</a>
%H A123552 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,0,-1).
%F A123552 G.f.: 1/((1-x)*(1-x^3-x^4)).
%F A123552 From _Robert FERREOL_, Sep 12 2017: (Start)
%F A123552 a(n) = a(n-1) + a(n-3) - a(n-5) for n >= 5, with a(0)=a(1)=a(2)=1, a(3)=2, a(4)=3.
%F A123552 a(n) = a(n-3) + a(n-4) + 1 for n >= 4, with a(0)=a(1)=a(2)=1, a(3)=2.
%F A123552 a(n) - a(n-1) = A017817(n). (End)
%t A123552 a=b=c=d=0;Table[e=a+b+1;a=b;b=c;c=d;d=e,{n,100}] (* _Vladimir Joseph Stephan Orlovsky_, Feb 26 2011*)
%t A123552 CoefficientList[Series[1/(1 - x - x^3 + x^5), {x, 0, 53}], x] (* _Michael De Vlieger_, Sep 15 2017 *)
%o A123552 (PARI) x='x+O('x^99); Vec(1/(1-x-x^3+x^5)) \\ _Altug Alkan_, Sep 12 2017
%Y A123552 Number of nodes at n-th generation in A123015.
%K A123552 nonn,easy
%O A123552 0,4
%A A123552 _Christian G. Bower_, Nov 14 2006