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 A077879 #14 Apr 30 2025 21:04:48
%S A077879 1,1,3,5,9,17,29,53,93,165,293,517,917,1621,2869,5077,8981,15893,
%T A077879 28117,49749,88021,155733,275541,487509,862549,1526101,2700117,
%U A077879 4777301,8452437,14954837,26459477,46814549,82828629,146548053,259286357,458753365,811668821
%N A077879 Expansion of (1-x)^(-1)/(1-2*x^2-2*x^3).
%H A077879 Harvey P. Dale, <a href="/A077879/b077879.txt">Table of n, a(n) for n = 0..1000</a>
%H A077879 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,0,-2).
%F A077879 a(n) = sum(k=1..n, sum(j=floor((4*k-n)/3)..floor((4*k-n)/2), binomial(j,n-4*k+3*j)*(-1)^(k-j)*binomial(k,j)*2^(n-3*k+2*j))), n>0, a(0)=1. - _Vladimir Kruchinin_, May 25 2011
%t A077879 CoefficientList[Series[(1-x)^(-1)/(1-2x^2-2x^3),{x,0,40}],x] (* or *) LinearRecurrence[{1,2,0,-2},{1,1,3,5},40] (* _Harvey P. Dale_, Sep 22 2016 *)
%o A077879 (Maxima)
%o A077879 a(n):=sum(sum(binomial(j,n-4*k+3*j)*(-1)^(k-j)*binomial(k,j)*2^(n-3*k+2*j),j,floor((4*k-n)/3),floor((4*k-n)/2)),k,1,n); /* _Vladimir Kruchinin_, May 25 2011 */
%K A077879 nonn
%O A077879 0,3
%A A077879 _N. J. A. Sloane_, Nov 17 2002