Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero and first differences in -2..2.
A209026
Number of n-bead necklaces labeled with numbers -2..2 allowing reversal, with sum zero and first differences in -2..2.
Terms
- a(0) =1a(1) =2a(2) =2a(3) =6a(4) =11a(5) =33a(6) =86a(7) =278a(8) =873a(9) =2938a(10) =9904a(11) =34321a(12) =119673a(13) =422725a(14) =1502590a(15) =5381671a(16) =19377063a(17) =70138385a(18) =254978018a(19) =930709334a(20) =3409356533a(21) =12530190100a(22) =46188325542a(23) =170723964752a(24) =632624262841
External references
- oeis: A209026