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 A006748 Number of diagonally symmetric polyominoes with n cells. (Formerly M0366) 20

%I M0366

%S 0,0,1,0,2,2,7,5,26,22,91,79,326,301,1186,1117,4352,4212,16119,15849,

%T 60174,60089,226146,228426,854803,872404,3247207,3342579

%N Number of diagonally symmetric polyominoes with n cells.

%C This sequence counts polyominoes with exactly the symmetry group of order 2 generated by a single reflection about a diagonal.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H Tomás Oliveira e Silva, <a href="http://sweet.ua.pt/tos/animals.html">Enumeration of polyominoes</a>

%H D. H. Redelmeier, <a href="http://dx.doi.org/10.1016/0012-365X(81)90237-5">Counting polyominoes: yet another attack</a>, Discrete Math., 36 (1981), 191-203.

%H D. H. Redelmeier, <a href="/A056877/a056877.png">Table 3</a> of Counting polyominoes...

%Y Cf. A000105, A001168, A006746, A056877, A006748, A056878, A006747.

%Y Sequences classifying polyominoes by symmetry group: A000105, A006746, A006747, A006748, A006749, A056877, A056878, A142886, A144553, A144554.

%K nonn

%O 1,5

%A _N. J. A. Sloane_.

%E Extended to n=28 by Tomás Oliveira e Silva.

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Last modified October 19 03:15 EDT 2019. Contains 328211 sequences. (Running on oeis4.)