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 A077927 #9 Jul 08 2022 11:48:24 %S A077927 1,-1,3,-7,17,-39,93,-219,517,-1219,2877,-6787,16013,-37779,89133, %T A077927 -210291,496141,-1170547,2761677,-6515635,15372365,-36268083,85567437, %U A077927 -201879603,476295373,-1123725619,2651210445,-6255011635,14757474509,-34817369907,82144763085,-193804475187 %N A077927 Expansion of (1-x)^(-1)/(1+2*x+2*x^3). %H A077927 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (-1,2,-2,2). %F A077927 a(n) = -a(n-1) + 2 a(n-2) - 2 a(n-3) + 2 a(n-4) - _N-E. Fahssi_, Mar 29 2008 %F A077927 a(n) -a(n-1) = (-1)^(n+1)*A052912(n). - _R. J. Mathar_, Jul 08 2022 %K A077927 sign,easy %O A077927 0,3 %A A077927 _N. J. A. Sloane_, Nov 17 2002