Number of bracelets (turn over necklaces) with n red, 1 pink and n - 3 blue beads; also reversible strings with n red and n-3 blue beads.
A005656
Number of bracelets (turn over necklaces) with n red, 1 pink and n - 3 blue beads; also reversible strings with n red and n-3 blue beads.
Terms
- a(0) =0a(1) =0a(2) =1a(3) =3a(4) =12a(5) =44a(6) =170a(7) =651a(8) =2520a(9) =9752a(10) =37854a(11) =147070a(12) =572264a(13) =2229096a(14) =8692788a(15) =33933459a(16) =132594480a(17) =518584880a(18) =2029976630a(19) =7952706234a(20) =31179618184a(21) =122331419080a(22) =480283635468
External references
- oeis: A005656