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Number of hexagonal polyominoes (or polyhexes, A000228) with perimeter 2n.
8

%I #22 Jun 17 2022 03:18:14

%S 0,0,1,0,1,1,3,2,12,14,50,98,313,750,2308,6270

%N Number of hexagonal polyominoes (or polyhexes, A000228) with perimeter 2n.

%H Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/IsopolyH.htm">Isoperimetrical Polyhexes</a>

%H <a href="/A057779/a057779.gif">Picture from Andrew Clarke's page showing the polyhexes of perimeters 6, 8, ... 16.</a>

%Y Cf. A000228, A000105, A057730, A258206 (counts only polyhexes without holes).

%K nonn,nice,more

%O 1,7

%A _N. J. A. Sloane_, Oct 29 2000

%E Link updated by _William Rex Marshall_, Dec 16 2009

%E a(13)-a(16) from _John Mason_, Jul 26 2021