login
A254211
Number of length n 1..(1+2) arrays with no leading or trailing partial sum equal to a prime and no consecutive values equal.
3
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
OFFSET
1,57
COMMENTS
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
LINKS
EXAMPLE
All solutions for n=5:
..1
..3
..2
..3
..1
CROSSREFS
Column k=1 of A254218.
Sequence in context: A326368 A197343 A289941 * A086501 A204241 A053115
KEYWORD
nonn,look,nice
AUTHOR
R. H. Hardin, Jan 26 2015
STATUS
approved