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 A083335 #17 Dec 14 2024 13:48:06
%S A083335 1,1,7,12,59,119,533,1128,4921,10561,45727,98532,425699,918359,
%T A083335 3965213,8557008,36940081,79725121,344150647,742776252,3206305739,
%U A083335 6920186999,29871902693,64472837688,278305188841,600669377281,2592864698767,5596211585172,24156746664179
%N A083335 a(n) = 12*a(n-2) - 25*a(n-4) with initial terms 1,1,7,12.
%C A083335 A083334(n)/a(n) converges to sqrt(11).
%H A083335 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,12,0,-25).
%F A083335 G.f.: (1 + x - 5*x^2) / (1 - 12*x^2 + 25*x^4).
%t A083335 CoefficientList[Series[(1+x-5x^2)/(1-12x^2+25x^4), {x, 0, 30}], x]
%t A083335 LinearRecurrence[{0,12,0,-25},{1,1,7,12},30] (* _Harvey P. Dale_, Mar 19 2013 *)
%Y A083335 Cf. A010468 (sqrt(11)), A083334.
%K A083335 nonn,easy
%O A083335 0,3
%A A083335 Mario Catalani (mario.catalani(AT)unito.it), Apr 26 2003