Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and first differences in -1..1.
A209025
Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and first differences in -1..1.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =4a(6) =6a(7) =13a(8) =21a(9) =45a(10) =83a(11) =181a(12) =362a(13) =794a(14) =1676a(15) =3703a(16) =8049a(17) =17925a(18) =39679a(19) =88980a(20) =199308a(21) =449714a(22) =1015574a(23) =2303940a(24) =5234731a(25) =11931095a(26) =27239911a(27) =62337821a(28) =142894336a(29) =328168558
External references
- oeis: A209025