%I
%S 0,0,0,1,6,37,183,876,3930,17179,73095,306323,1267266,5198374,
%T 21182337,85910040,347187210,1399447578,5629911015,22616239535,
%U 90754854843,363890053582,1458172596903,5840531328120,23385650196084
%N Number of primitive (aperiodic) reversible string structures with n beads using exactly four different colors.
%C A string and its reverse are considered to be equivalent. Permuting the colors will not change the structure.
%D M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]
%F A056333(n)A056332(n).
%Y Column 4 of A276544.
%Y Cf. A056320.
%K nonn
%O 1,5
%A _Marks R. Nester_
