Number of parallelogram polyominoes of site-perimeter n (also called staircase polyominoes, although that term is overused).

A075125

Number of parallelogram polyominoes of site-perimeter n (also called staircase polyominoes, although that term is overused).

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =0a(5) =2a(6) =2a(7) =5a(8) =10a(9) =21a(10) =46a(11) =102a(12) =230a(13) =526a(14) =1216a(15) =2838a(16) =6678a(17) =15825a(18) =37734a(19) =90469a(20) =217962a(21) =527418a(22) =1281250a(23) =3123603a(24) =7639784a(25) =18740795a(26) =46096732a(27) =113666820a(28) =280928470a(29) =695796891

External references