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A229718
Number of arrays of length 2 that are sums of n consecutive elements of length 2+n-1 permutations of 0..2+n-2, and no two consecutive rises or falls in the latter permutation.
0
2, 4, 8, 18, 26, 40, 52, 70, 86, 108, 128, 154, 178, 208
OFFSET
1,1
COMMENTS
Row 2 of A229717.
FORMULA
Empirical: a(n) = 2*a(n-1) - 2*a(n-3) + a(n-4) for n > 5.
EXAMPLE
Some solutions for n=4:
10 6 9 7 9 8 8 8 6 8 7 6 7 10 10 7
7 9 8 8 6 10 7 6 8 9 10 7 9 8 9 6
CROSSREFS
Sequence in context: A171719 A185178 A351471 * A246469 A092507 A347036
KEYWORD
nonn,more
AUTHOR
R. H. Hardin, Sep 27 2013
STATUS
approved