%I A056471
%S A056471 1,1,2,2,5,5,15,15,52,52,203,203,876,876,4111,4111,20648,20648,109299,
%T A056471 109299,601492,601492,3403127,3403127,19628064,19628064,114700315,
%U A056471 114700315,676207628,676207628,4010090463
%N A056471 Number of palindromic structures using a maximum of six different symbols.
%C A056471 Permuting the symbols will not change the structure.
%D A056471 M. R. Nester (1999). Mathematical investigations of some plant interaction 
               designs. PhD Thesis. University of Queensland, Brisbane, Australia.
%F A056471 Sum stirling2( [(n+1)/2], k) for k from 1 to 6.
%Y A056471 Cf. A056452.
%Y A056471 Sequence in context: A097438 A055879 A056470 this_sequence A164904 A083849 
               A063501
%Y A056471 Adjacent sequences: A056468 A056469 A056470 this_sequence A056472 A056473 
               A056474
%K A056471 nonn
%O A056471 1,3
%A A056471 Marks R. Nester (nesterm(AT)dpi.qld.gov.au)