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.

2, 4, 8, 18, 26, 40, 52, 70, 86, 108, 128, 154, 178, 208

Offset

1,1

Comments

Row 2 of A229717.

Links

Table of n, a(n) for n=1..14.

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

Adjacent sequences: A229715 A229716 A229717 * A229719 A229720 A229721

Keyword

nonn,more

Author

R. H. Hardin, Sep 27 2013

Status

approved