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 A145117 #8 Sep 24 2016 11:08:10 %S A145117 1,2,4,8,16,32,64,128,256,512,1024,2047,4091,8175,16335,32639,65215, %T A145117 130303,260351,520191,1039359,2076672,4149254,8290334,16564334, %U A145117 33096030,66126846,132123390,263986430,527452670,1053865982,2105655293,4207161333,8406032333 %N A145117 Numbers of length n binary words with fewer than 9 0-digits between any pair of consecutive 1-digits. %H A145117 Vincenzo Librandi, <a href="/A145117/b145117.txt">Table of n, a(n) for n = 0..1000</a> %H A145117 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (3, -2, 0, 0, 0, 0, 0, 0, 0, -1, 1). %F A145117 G.f.: (1-x+x^10)/(1-3*x+2*x^2+x^10-x^11). %e A145117 a(11) = 2047 = 2^11-1, because 10000000001 is the only binary word of length 11 with not less than 9 0-digits between any pair of consecutive 1-digits. %p A145117 a:= n-> (Matrix([[2,1$10]]). Matrix(11, (i, j)-> if i=j-1 then 1 elif j=1 then [3, -2, 0$7, -1, 1][i] else 0 fi)^n)[1, 2]: seq(a(n), n=0..35); %t A145117 CoefficientList[Series[(1 - x + x^10) / (1 - 3 x + 2 x^2 + x^10 - x^11), {x, 0, 40}], x] (* _Vincenzo Librandi_, Jun 06 2013 *) %t A145117 LinearRecurrence[{3,-2,0,0,0,0,0,0,0,-1,1},{1,2,4,8,16,32,64,128,256,512,1024},40] (* _Harvey P. Dale_, Sep 24 2016 *) %Y A145117 9th column of A145111. %K A145117 nonn,easy %O A145117 0,2 %A A145117 _Alois P. Heinz_, Oct 02 2008