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 A106250 #9 Jun 13 2015 00:51:48
%S A106250 1,0,1,2,2,3,2,3,4,4,5,4,5,6,6,7,6,7,8,8,9,8,9,10,10,11,10,11,12,12,
%T A106250 13,12,13,14,14,15,14,15,16,16,17,16,17,18,18,19,18,19,20,20,21,20,21,
%U A106250 22,22,23,22,23,24,24,25,24,25,26,26,27,26,27,28,28,29,28,29,30,30,31,30
%N A106250 Expansion of (1-x+x^2+x^3)/(1-x-x^5+x^6).
%H A106250 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,1,-1).
%F A106250 G.f.: (1-x+x^2+x^3)/(1-x-x^5+x^6)=(1+x^2+2x^3+2x^4+x^5+2x^6+x^7)/(1-x^5)^2; a(n)=sum{k=0..n, -mu(k mod 5)}.
%t A106250 CoefficientList[Series[(1-x+x^2+x^3)/(1-x-x^5+x^6),{x,0,120}],x] (* or *) LinearRecurrence[{1,0,0,0,1,-1},{1,0,1,2,2,3},121] (* _Harvey P. Dale_, Apr 26 2011 *)
%Y A106250 Cf. A008611.
%K A106250 easy,nonn
%O A106250 0,4
%A A106250 _Paul Barry_, Apr 27 2005