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 A153266 #9 Jun 02 2025 01:16:25 %S A153266 13,-19,162,-423,2281,-7582,34365,-126891,535234,-2068495,8463633, %T A153266 -33358014,134731957,-535524643,2151008226,-8580707127,34383896185, %U A153266 -137375707486,549921394029,-2198589761115,8797227925378 %N A153266 a(n) = -4*a(n-3) + 11*a(n-2) - a(n-1), a(0) = 13, a(1) = -19, a(2) = 162. %C A153266 a(n) + A153267(n) = 4*A001519(n) (apart from initial terms). The generating floretion Z = X*Y with X = 1.5'i + 0.5i' + .25(ii + jj + kk + ee) and Y = 0.5'i + 1.5i' + .25(ii + jj + kk + ee) %H A153266 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-1, 11, -4). %F A153266 a(n) = 2*(-4)^n + (-2/5*sqrt(5)-1)*(3/2+1/2*sqrt(5))^n + (2/5*sqrt(5)-1)*(3/2-1/2*sqrt(5))^n %F A153266 a(n)=A001519(n+3)+8*(-4)^n. G.f.: (13-6x)/((1+4x)(1-3x+x^2)). [From _R. J. Mathar_, Jan 05 2009] %e A153266 a(4) = -1*(-423) + 11*162 - 4*(-19) = 2281 %Y A153266 A153267, A153265, A001519 %K A153266 easy,sign %O A153266 0,1 %A A153266 _Creighton Dement_, Jan 02 2009