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Number of step cyclic shifted sequence structures of length n using an infinite alphabet.
2

%I #10 Oct 16 2017 02:41:29

%S 1,2,3,7,8,37,37,223,468,3203,6398,93103,178663,2282131,11561896,

%T 82120878,304719416,6316222138,17055376113,323332552319,1884432112761,

%U 20485110860448,87256977757852,2322728266726152,9277181270824996,159074512149044084,1122874592283076868

%N Number of step cyclic shifted sequence structures of length n using an infinite alphabet.

%C See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. Permuting the symbols 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]

%o (PARI) \\ see A056391 for Polya enumeration functions

%o a(n) = NonequivalentStructs(CyclicStepShiftPerms(n), n); \\ _Andrew Howroyd_, Oct 14 2017

%Y Row sums of A288627.

%Y Cf. A056391, A056371, A288621.

%K nonn

%O 1,2

%A _Andrew Howroyd_, Jun 11 2017