Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.
A209478
Number of n-bead necklaces labeled with numbers -1..1 allowing reversal, with sum zero and avoiding the patterns z z+1 z+2 and z z-1 z-2.
Terms
- a(0) =1a(1) =2a(2) =1a(3) =4a(4) =4a(5) =11a(6) =15a(7) =43a(8) =77a(9) =199a(10) =423a(11) =1080a(12) =2514a(13) =6355a(14) =15529a(15) =39429a(16) =98875a(17) =252551a(18) =643133a(19) =1653677a(20) =4254070a(21) =11005241a(22) =28518931a(23) =74179434a(24) =193328017a(25) =505236093a(26) =1322919905a(27) =3471492272a(28) =9125743338
External references
- oeis: A209478