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Building block is 2 hexagons side-by-side; sequence gives number of pieces (polydohexes) that can be formed from n such pairs of hexagons.
1

%I #11 Jul 02 2022 04:14:39

%S 1,6,74,1257,25379,544108,12037738

%N Building block is 2 hexagons side-by-side; sequence gives number of pieces (polydohexes) that can be formed from n such pairs of hexagons.

%D Computed by Brendan Owen.

%H Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/PolyX/index.htm?PolyX.htm">Other Polyforms</a>

%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a057/A057783.java">Java program</a> (github)

%Y Cf. A000228, A000105, A000665.

%K nonn,hard,more,nice

%O 1,2

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

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

%E a(7) from _Sean A. Irvine_, Jul 02 2022