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Number of circular permutations of 1..n with no adjacent three summing to a prime, ignoring rotations and reversals
0

%I #5 May 12 2012 16:20:55

%S 0,0,1,0,2,4,14,48,432,2316,24743,223506,2537594,26771235,344781871,

%T 3927465497,53273396228,660418431957

%N Number of circular permutations of 1..n with no adjacent three summing to a prime, ignoring rotations and reversals

%e Some solutions for n=8

%e ..5....6....4....2....2....5....5....6....3....3....4....2....2....5....2....2

%e ..1....1....1....1....1....1....1....1....1....1....1....1....1....1....1....1

%e ..6....7....7....7....3....8....8....7....8....6....7....7....3....6....6....5

%e ..8....2....6....6....4....3....7....8....7....8....6....8....4....7....8....4

%e ..4....5....2....8....5....7....6....5....5....2....8....6....8....3....4....6

%e ..3....3....8....4....7....2....2....3....6....5....2....4....6....4....3....8

%e ..7....4....5....3....8....6....4....4....4....7....5....5....7....2....7....7

%e ..2....8....3....5....6....4....3....2....2....4....3....3....5....8....5....3

%K nonn

%O 1,5

%A _R. H. Hardin_ May 12 2012