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A254211
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Number of length n 1..(1+2) arrays with no leading or trailing partial sum equal to a prime and no consecutive values equal.
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3
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1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 18, 456, 2178, 3376, 2222, 720, 158, 24, 0, 0, 0, 0, 0, 10, 122, 204, 116, 26, 2, 10, 72, 84, 25, 6, 4, 0, 0, 0, 0, 0
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OFFSET
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1,57
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COMMENTS
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These are vectors [u_1 ... u_n] such that
(i) u_i = 1,2 or 3,
(ii) u_i != u_{i+1},
(iii) Sum_{i=1..k} u_i != prime for k=1..n,
(iv) Sum_{i=k..n} u_i != prime for k=1..n.
Conjecture: There are infinitely many n > 0 with a(n) > 0. - Alois P. Heinz, Jan 27 2015
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LINKS
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EXAMPLE
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All solutions for n=5:
..1
..3
..2
..3
..1
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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