Number of achiral color patterns (set partitions) for a row or loop of length n using exactly 4 colors (sets).

A304974

Number of achiral color patterns (set partitions) for a row or loop of length n using exactly 4 colors (sets).

Terms

    a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =2a(6) =9a(7) =16a(8) =53a(9) =90a(10) =265a(11) =440a(12) =1221a(13) =2002a(14) =5369a(15) =8736a(16) =22933a(17) =37130a(18) =96105a(19) =155080a(20) =397541a(21) =640002a(22) =1629529a(23) =2619056a(24) =6636213a(25) =10653370a(26) =26899145a(27) =43144920a(28) =108659461a(29) =174174002

External references