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A057422
Axially symmetric (about axis 2) 2n-celled polyominoes with 1 hole.
0
0, 2, 4, 12, 24, 57, 112, 244, 483, 998, 1979
OFFSET
4,2
CROSSREFS
Cf. A056880.
Sequence in context: A004645 A045687 A233411 * A036045 A331392 A100538
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 05 2000
STATUS
approved