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Number of primitive (aperiodic) words of length n which contain exactly four different symbols.
1

%I #7 Aug 22 2017 20:53:07

%S 0,0,0,24,240,1560,8400,40800,186480,818280,3498000,14674440,60780720,

%T 249393480,1016542560,4123132800,16664094960,67171179600,270232006800,

%U 1085569963080,4356217672800,17466683473800

%N Number of primitive (aperiodic) words of length n which contain exactly four different symbols.

%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 sum mu(d)*A000919(n/d) where d|n.

%F Seems to be n * A056289.

%Y Cf. A000302, A000919, A054719.

%K nonn

%O 1,4

%A _Marks R. Nester_