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 A185341 #28 Jun 29 2017 17:08:30
%S A185341 1,1,1,1,1,1,1,1,5,10,6,21,77,55,145,899,868,1988,38411,90347,95357,
%T A185341 637807,3506263,2382501,19519203,649945741,911672929,3857971277,
%U A185341 130630182325,366719420575,764101349503,12533062448579,136235802233249
%N A185341 Denominators of u(n) where u(n) = (u(n-1) + u(n-2)) / u(n-3), with u(1) = u(2) = u(3) = 1.
%H A185341 Seiichi Manyama, <a href="/A185341/b185341.txt">Table of n, a(n) for n = 1..262</a>
%F A185341 u(4 - n) = u(n) for all n in Z.
%F A185341 0 = u(n) * u(n+3) - u(n+1) - u(n+2) for all n in Z. - _Michael Somos_, Nov 01 2014
%e A185341 u(1), ... = 1, 1, 1, 2, 3, 5, 4, 3, 7/5, 11/10, 5/6, 29/21, 155/77, 224/55, 639/145, ...
%t A185341 Denominator[RecurrenceTable[{u[1] == u[2] == u[3] == 1, u[n] == (u[n - 1] + u[n - 2])/u[n - 3]}, u, {n, 50}]] (* _G. C. Greubel_, Jun 27 2017 *)
%o A185341 (PARI) {u(n) = local(v = [1, 1, 1]); if( n<1, n = 4-n); if( n<4, 1, for( k=4, n, v = [v[2], v[3], (v[2] + v[3]) / v[1]]); denominator( v[3] ))};
%Y A185341 Cf. A068508, A185332, A205303.
%K A185341 nonn,frac
%O A185341 1,9
%A A185341 _Michael Somos_, Jan 27 2012