%I A056303
%S A056303 0,1,1,2,3,5,9,16,28,51,93,170,315,585,1091,2048,3855,7280,13797,26214,
%T A056303 49929,95325,182361,349520,671088,1290555,2485504,4793490,9256395,
%U A056303 17895679,34636833
%N A056303 Number of primitive (period n) n-bead necklace structures using exactly 
               two different colored beads.
%C A056303 Turning over the necklace is not allowed. Colors may be permuted without 
               changing the necklace structure. Identical to A000048 for n>1.
%D A056303 M. R. Nester (1999). Mathematical investigations of some plant interaction 
               designs. PhD Thesis. University of Queensland, Brisbane, Australia.
%F A056303 Sum mu(d)*A056295(n/d) where d divides n . Alternatively, A000048(n)-A000007(n-1)..
%Y A056303 Cf. A001037.
%Y A056303 Sequence in context: A114834 A143961 A128023 this_sequence A000048 A074099 
               A006788
%Y A056303 Adjacent sequences: A056300 A056301 A056302 this_sequence A056304 A056305 
               A056306
%K A056303 nonn
%O A056303 1,4
%A A056303 Marks R. Nester (nesterm(AT)dpi.qld.gov.au)