Number of fixed polyominoes with perimeter 2n.

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =7a(5) =28a(6) =124a(7) =588a(8) =2943a(9) =15364a(10) =82976a(11) =460760a(12) =2618858a(13) =15183502a(14) =89555364a(15) =536222178