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 A005398 M4512 #34 Apr 05 2024 19:46:30
%S A005398 8,33,168,970,6168,42069,301376,2241420,17173224,134806948,1079802216,
%T A005398 8798329080,72748583832,609220407150,5158999447488
%N A005398 Number of n-step polygons on f.c.c. lattice.
%D A005398 A. J. Guttmann, Polygons, Polyominoes and Polycubes, Lecture Notes in Physics Volume 775, 2009, Chapter 16.
%D A005398 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A005398 M. F. Sykes et al., <a href="http://dx.doi.org/10.1063/1.1705066">Lattice constant systems and graph theory</a>, J. Math. Phys., 7 (1966), 1557-1572.
%H A005398 <a href="/index/Fa#fcc">Index entries for sequences related to f.c.c. lattice</a>
%t A005398 A001337 = Cases[Import["https://oeis.org/A001337/b001337.txt", "Table"], {_, _}][[All, 2]];
%t A005398 a[n_] := A001337[[n]]/(2n);
%t A005398 a /@ Range[3, 17] (* _Jean-François Alcover_, Jan 20 2020 *)
%Y A005398 Equals A001337(n) / (2n).
%K A005398 nonn,more,nice
%O A005398 3,1
%A A005398 _N. J. A. Sloane_
%E A005398 More terms from _Ruperto Corso_, Dec 19 2011
%E A005398 a(15) and a(16) from _Sean A. Irvine_, Mar 30 2017
%E A005398 a(17) from _Bert Dobbelaere_, Jan 14 2019