Number of diagonally symmetric polyominoes with n cells.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =2a(5) =2a(6) =7a(7) =5a(8) =26a(9) =22a(10) =91a(11) =79a(12) =326a(13) =301a(14) =1186a(15) =1117a(16) =4352a(17) =4212a(18) =16119a(19) =15849a(20) =60174a(21) =60089a(22) =226146a(23) =228426a(24) =854803a(25) =872404a(26) =3247207a(27) =3342579a(28) =12389106a(29) =12850662