Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the
OEIS Foundation home page.
Polyominoes with n cells and at least one line of reflection symmetry. - Joshua Zucker, Mar 08 2008
Table of n, a(n) for n=1..36.
a(n) = A000105(n) - A030228(n) = 2*A000105(n) - A000988(n). - Andrew Howroyd, Dec 04 2018
Cf. A000105, A000988, A006746, A030228.
Sequence in context: A135452 A077027 A030436 * A180272 A319436 A061551
Adjacent sequences: A030224 A030225 A030226 * A030228 A030229 A030230
David W. Wilson
a(23)-a(36) from Andrew Howroyd, Dec 04 2018