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 A143450 #28 Aug 08 2019 18:51:24
%S A143450 1,3,5,7,9,11,13,15,17,23,33,47,65,87,113,143,177,223,289,383,513,687,
%T A143450 913,1199,1553,1999,2577,3343,4369,5743,7569,9967,13073,17071,22225,
%U A143450 28911,37649,49135,64273,84207,110353,144495,188945,246767,322065,420335,548881
%N A143450 Expansion of 1/(x^k*(1-x-2*x^(k+1))) for k=7.
%C A143450 a(n) is also the number of length n ternary words with at least 7 0-digits between any other digits.
%C A143450 The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n>=15, 3*a(n-15) equals the number of 3-colored compositions of n with all parts >=8, such that no adjacent parts have the same color. - _Milan Janjic_, Nov 27 2011
%H A143450 Alois P. Heinz, <a href="/A143450/b143450.txt">Table of n, a(n) for n = 0..1000</a>
%H A143450 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,2).
%F A143450 G.f.: 1/(x^7*(1-x-2*x^8)).
%F A143450 a(n) = 2n+1 if n<=8, else a(n) = a(n-1) + 2a(n-8). - _Milan Janjic_, Mar 09 2015
%p A143450 a:= proc(k::nonnegint) local n,i,j; if k=0 then unapply(3^n,n) else unapply((Matrix(k+1, (i,j)-> if (i=j-1) or j=1 and i=1 then 1 elif j=1 and i=k+1 then 2 else 0 fi)^(n+k))[1,1], n) fi end(7): seq(a(n), n=0..61);
%t A143450 Series[1/(1-x-2*x^8), {x, 0, 61}] // CoefficientList[#, x]& // Drop[#, 7]& (* _Jean-François Alcover_, Feb 13 2014 *)
%Y A143450 7th column of A143453.
%K A143450 nonn,easy
%O A143450 0,2
%A A143450 _Alois P. Heinz_, Aug 16 2008