Number of T-frame polyominoes with n cells.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =6a(6) =10a(7) =19a(8) =28a(9) =44a(10) =60a(11) =86a(12) =110a(13) =146a(14) =182a(15) =233a(16) =278a(17) =343a(18) =403a(19) =490a(20) =557a(21) =664a(22) =749a(23) =879a(24) =978a(25) =1132a(26) =1237a(27) =1435a(28) =1551a(29) =1771