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 A066931 #15 Oct 19 2017 03:13:58 %S A066931 1,1,6,113,20174,22306955,123222909271,3283834214485890, %T A066931 421263391026827547540,260028731850596651411721718, %U A066931 772086476515163830856527013278243,11025620741283840573496993339545350520150,757129347300072898736973484532998417574513923224 %N A066931 Number of ways to tile hexagon of edge n with diamonds of side 1, not counting rotations and reflections as different. %H A066931 R. K. Guy and D. J. Reble, <a href="/A066931/a066931.txt">Illustration of initial terms</a> %H A066931 P. J. Taylor, <a href="http://cheddarmonk.org/papers/distinct-dimer-hex-tilings.pdf">Counting distinct dimer hex tilings</a>, Preprint, 2015. %F A066931 From _Peter J. Taylor_, Jun 17 2015: (Start) %F A066931 For odd n, a(n) = A008793(n)/12 + A049505(n)/4 + A006366(n)/6. %F A066931 For even n, a(n) = A008793(n)/12 + A049505(n)/4 + A006366(n)/6 + A181119(n/2)/4 + A259049(n/2)/12 + A049503(n/2)/6. %F A066931 See Taylor link. %F A066931 (End) %Y A066931 Cf. A008793. %K A066931 nonn %O A066931 0,3 %A A066931 _R. K. Guy_, Feb 05 2002 %E A066931 One more term from _Don Reble_, Feb 07 2002 %E A066931 More terms from _Peter J. Taylor_, Jun 17 2015