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 A012880 #10 Jul 08 2025 02:47:22 %S A012880 0,1,3,11,44,179,730,2978,12149,49563,202197,824882,3365185,13728594, %T A012880 56007112,228486369,932131991,3802721591,15513566360,63289077427, %U A012880 258193843286,1053326473082,4297146069693,17530618299423 %N A012880 a(n+3) = 5*a(n+2)-4*a(n+1)+a(n). %H A012880 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4,1). %F A012880 G.f. x*(-1+2*x) / ( -1+5*x-4*x^2+x^3 ). a(n) = A012814(n)-2*A012814(n-1). - _R. J. Mathar_, Sep 20 2012 %Y A012880 Cf. A012855. %K A012880 nonn,easy %O A012880 0,3 %A A012880 _N. J. A. Sloane_