Number of 2n-bead black-white reversible strings with n black beads and fundamental period 2n.
A045627
Number of 2n-bead black-white reversible strings with n black beads and fundamental period 2n.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =9a(4) =34a(5) =125a(6) =459a(7) =1715a(8) =6432a(9) =24300a(10) =92375a(11) =352715a(12) =1352034a(13) =5200299a(14) =20058297a(15) =77558625a(16) =300540160a(17) =1166803109a(18) =4537567188a(19) =17672631899a(20) =68923264250a(21) =269128935495
External references
- oeis: A045627