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 A168495 #11 Sep 08 2022 08:45:49
%S A168495 1,1,3,27,243,6561,531441,43046721,10460353203,7625597484987,
%T A168495 5559060566555523,12157665459056928801,79766443076872509863361,
%U A168495 523347633027360537213511521,10301051460877537453973547267843
%N A168495 a(n) = 3^floor(n^2/3).
%C A168495 Hankel transform of A168494. Trivial Somos-4 sequence linked to elliptic curve y^2=1-10x+25x^2-12x^3.
%H A168495 Vincenzo Librandi, <a href="/A168495/b168495.txt">Table of n, a(n) for n = 0..79</a>
%F A168495 a(n) = 9*a(n-1)*a(n-3)/a(n-4).
%t A168495 Table[3^Floor[n^2/3], {n,0,20}] (* _G. C. Greubel_, Sep 18 2018 *)
%o A168495 (Magma) [3^Floor(n^2/3): n in [0..15]]; // _Vincenzo Librandi_, Sep 15 2011
%o A168495 (PARI) vector(20, n, n--; 3^floor(n^2/3)) \\ _G. C. Greubel_, Sep 18 2018
%K A168495 nonn,easy
%O A168495 0,3
%A A168495 _Paul Barry_, Nov 27 2009