Number of configurations, excluding reflections and black-white interchanges, of n black and n white beads on a string.
A045723
Number of configurations, excluding reflections and black-white interchanges, of n black and n white beads on a string.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =7a(4) =23a(5) =71a(6) =252a(7) =890a(8) =3299a(9) =12283a(10) =46508a(11) =176870a(12) =677294a(13) =2602198a(14) =10034104a(15) =38787572a(16) =150289699a(17) =583434323a(18) =2268861516a(19) =8836447022a(20) =34461940538a(21) =134564992898a(22) =526025965864
External references
- oeis: A045723