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 A143452 #32 Aug 08 2019 18:51:55
%S A143452 1,3,5,7,9,11,13,15,17,19,21,27,37,51,69,91,117,147,181,219,261,315,
%T A143452 389,491,629,811,1045,1339,1701,2139,2661,3291,4069,5051,6309,7931,
%U A143452 10021,12699,16101,20379,25701,32283,40421,50523,63141,79003,99045,124443,156645
%N A143452 Expansion of 1/(x^k*(1-x-2*x^(k+1))) for k=9.
%C A143452 a(n) is also the number of length n ternary words with at least 9 0-digits between any other digits.
%C A143452 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>=19, 3*a(n-19) equals the number of 3-colored compositions of n with all parts >=10, such that no adjacent parts have the same color. - _Milan Janjic_, Nov 27 2011
%H A143452 Alois P. Heinz, <a href="/A143452/b143452.txt">Table of n, a(n) for n = 0..1000</a>
%H A143452 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,0,2).
%F A143452 G.f.: 1/(x^9*(1-x-2*x^10)).
%F A143452 a(n) = 2n+1 if n<=10, else a(n) = a(n-1) + 2a(n-10). - _Milan Janjic_, Mar 09 2015
%p A143452 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(9): seq(a(n), n=0..64);
%t A143452 Series[1/(1-x-2*x^10), {x, 0, 64}] // CoefficientList[#, x]& // Drop[#, 9]& (* _Jean-François Alcover_, Feb 13 2014 *)
%t A143452 LinearRecurrence[{1,0,0,0,0,0,0,0,0,2},{1,3,5,7,9,11,13,15,17,19},50] (* _Harvey P. Dale_, Nov 28 2015 *)
%Y A143452 9th column of A143453.
%K A143452 nonn,easy
%O A143452 0,2
%A A143452 _Alois P. Heinz_, Aug 16 2008