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A307454
a(n) is the number of canonical polygons with 2n edges having 2-fold rotational symmetry.
8
1, 3, 9, 33, 123, 513, 2077, 8759, 37184, 159508, 688446, 2993451, 13082724
OFFSET
2,2
KEYWORD
nonn,more
AUTHOR
Lars Blomberg, Apr 09 2019
STATUS
approved