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 A012866 #15 Jul 08 2025 02:47:16 %S A012866 0,1,2,6,23,93,379,1546,6307,25730,104968,428227,1746993,7127025, %T A012866 29075380,118615793,483904470,1974134558,8053670703,32855719753, %U A012866 134038050511,546821044246,2230808738939,9100797568222 %N A012866 a(n+3) = 5*a(n+2)-4*a(n+1)+a(n). %H A012866 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (5, -4, 1). %F A012866 G.f. x*(-1+3*x) / ( -1+5*x-4*x^2+x^3 ). - R. J. Mathar, Dec 22 2011 %F A012866 a(n) = A012814(n)-3*A012814(n-1). - _R. J. Mathar_, Sep 20 2012 %Y A012866 Cf. A012855. %K A012866 nonn,easy %O A012866 0,3 %A A012866 _N. J. A. Sloane_