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 A077851 #12 Aug 07 2015 02:41:05 %S A077851 1,3,7,17,41,97,229,541,1277,3013,7109,16773,39573,93365,220277, %T A077851 519701,1226133,2892821,6825045,16102357,37990357,89630805,211466325, %U A077851 498913365,1177088341,2777109333,6552045397,15458267477,36470753621,86045598037,203007731029 %N A077851 Expansion of (1-x)^(-1)/(1 - 2*x - 2*x^3). %H A077851 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2,2,-2). %p A077851 A052912 := proc(n) if n < 0 then 0; else coeftayl( 1/(1-2*x^3-2*x),x=0,n) ; end if; end proc: %p A077851 A077851 := proc(n) 2*(2*A052912(n)+A052912(n-1)+A052912(n-2))-1 ; %/3 ; end proc: %p A077851 seq(A077851(n),n=0..15) ; # _R. J. Mathar_, Mar 28 2011 %o A077851 (PARI) Vec((1-x)^(-1)/(1-2*x-2*x^3)+O(x^99)) \\ _Charles R Greathouse IV_, Sep 27 2012 %K A077851 nonn,easy %O A077851 0,2 %A A077851 _N. J. A. Sloane_, Nov 17 2002