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A038144 Number of planar n-hexes, or polyhexes (in the sense of A000228, so rotations and reflections count as the same shape) with at least one hole. 4

%I

%S 0,0,0,0,0,1,2,13,67,404,2323,13517,76570,429320,2373965,13004323,

%T 70641985,381260615,2046521491,10936624026,58228136539

%N Number of planar n-hexes, or polyhexes (in the sense of A000228, so rotations and reflections count as the same shape) with at least one hole.

%C Apparently the same as the number of hexagonal planar circulenes (planar rings of hexagons) with n cells, although the two sequences may in fact differ for large n.

%D J. V. Knop et al., On the total number of polyhexes, Match, No. 16 (1984), 119-134.

%H Craig Knecht, <a href="/A038144/a038144.png">Tiling of a fixed pattern of holes in a frame.</a>

%H Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyomino, polyhex and polyiamond tiling</a>

%Y Cf. A018190, A038143, A038147, A000228, A018190.

%K nonn

%O 1,7

%A _N. J. A. Sloane_

%E More terms from _Joseph Myers_, May 05 2002

%E Further terms from _Joseph Myers_, Nov 06 2003

%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007

%E Link edited by _Joseph Myers_, Nov 17 2010

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Last modified September 20 22:20 EDT 2019. Contains 327252 sequences. (Running on oeis4.)