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Arshon's sequence with a different start: start from 2 and replace the letters in odd positions using 1 -> 123, 2 -> 231, 3 -> 312 and the letters in even positions using 1 -> 321, 2-> 132, 3 -> 213.
2

%I #3 Mar 30 2012 17:31:07

%S 2,3,1,2,1,3,1,2,3,1,3,2,1,2,3,2,1,3,1,2,3,1,3,2,3,1,2,3,2,1,3,1,2,1,

%T 3,2,1,2,3,1,3,2,3,1,2,1,3,2,1,2,3,2,1,3,1,2,3,1,3,2,3,1,2,3,2,1,3,1,

%U 2,1,3,2,3,1,2,3,2,1,2,3,1,2,1,3,2,3,1,3,2,1,3,1,2,3,2,1,2,3,1,3,2,1,3,1,2

%N Arshon's sequence with a different start: start from 2 and replace the letters in odd positions using 1 -> 123, 2 -> 231, 3 -> 312 and the letters in even positions using 1 -> 321, 2-> 132, 3 -> 213.

%t f[n_List] := Block[{a = {}, l = Length[n], k = 1}, While[k < l + 1, If[ EvenQ[k], Switch[ n[[k]], 1, AppendTo[a, 321], 2, AppendTo[a, 132], 3, AppendTo[a, 213]], Switch[ n[[k]], 1, AppendTo[a, 123], 2, AppendTo[a, 231], 3, AppendTo[a, 312]]]; k++ ]; Flatten[ IntegerDigits /@ a]]; Take[ Nest[f, {2}, 5], 105]

%Y Inspired by A099054. Cf. A100337.

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Nov 17 2004