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 A221286 #42 Dec 23 2023 08:44:01
%S A221286 106276436867,35256392432,141532829299,176789221731,318322051030,
%T A221286 495111272761,813433323791,1308544596552,2121977920343,3430522516895,
%U A221286 5552500437238,8983022954133,14535523391371,23518546345504,38054069736875,61572616082379,99626685819254,161199301901633,260825987720887,422025289622520
%N A221286 Vsemirnov's sequence.
%C A221286 A primefree linear recurrence with no common factors. As of 2004 no such sequences with smaller starting terms were known.
%H A221286 Seiichi Manyama, <a href="/A221286/b221286.txt">Table of n, a(n) for n = 0..4733</a> (terms 0..1000 from Alois P. Heinz)
%H A221286 Arturas Dubickas, Aivaras Novikas, and Jonas Šiurys, <a href="http://dx.doi.org/10.1016/j.jnt.2010.03.015">A binary linear recurrence sequence of composite numbers</a>, Journal of Number Theory, Volume 130, Issue 8, August 2010, Pages 1737-1749.
%H A221286 D. Ismailescu and J. Son, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL17/Ismailescu/ism8.html">A New Kind of Fibonacci-Like Sequence of Composite Numbers</a>, J. Int. Seq. 17 (2014) # 14.8.2.
%H A221286 Maxim Vsemirnov, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL7/Vsemirnov/vsem5.html">A new Fibonacci-like sequence of composite numbers</a>, Journal of Integer Sequences 7:3 (2004).
%H A221286 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1,1).
%F A221286 a(n) = a(n-1) + a(n-2).
%F A221286 G.f.: (106276436867-71020044435*x)/(1-x-x^2).
%p A221286 a:= n-> (<<0|1>, <1|1>>^n. <<106276436867, 35256392432>>)[1, 1]:
%p A221286 seq(a(n), n=0..20); # _Alois P. Heinz_, Apr 04 2013
%t A221286 LinearRecurrence[{1, 1}, {106276436867, 35256392432}, 20] (* _Alonso del Arte_, Feb 05 2013 *)
%o A221286 (PARI) Vec((106276436867-71020044435*x)/(1-x-x^2)+O(x^30)) \\ _Charles R Greathouse IV_, Dec 09 2014
%Y A221286 Other primefree linear recurrences: A083104 (Graham 1964), A082411 (Nicol 1999), A083105 (Knuth 1990), A083216 (Wilf 1990).
%K A221286 nonn,easy
%O A221286 0,1
%A A221286 _Charles R Greathouse IV_, Feb 05 2013
%E A221286 Offset corrected by _Alois P. Heinz_, Apr 04 2013