login
A263788
Triangle read by rows: T(n,k) (n>=0, k>=0) is the number of permutations of n and convexity k.
0
1, 1, 2, 4, 0, 0, 2, 6, 2, 0, 8, 4, 4, 8, 6, 2, 28, 20, 32, 12, 12, 8, 16, 6, 106, 80, 156, 120, 132, 48, 48, 8, 32, 16, 352, 396, 708, 696, 1044, 624, 684, 240, 240, 8, 58, 36, 1174, 1654, 3698, 3716, 6396, 5832, 6756, 3936, 4176, 1440, 1440, 8, 98, 80, 3752
OFFSET
0,3
COMMENTS
The convexity of a permutation in one-line notation is the maximal value of twice an entry minus the sum of its neighbors.
The row lengths are 2n-2 starting for n>=3.
Row sums give A000142.
LINKS
FindStat - Combinatorial Statistic Finder, The convexity of a permutation.
EXAMPLE
Triangle begins:
1
1
2
4 0 0 2
6 2 0 8 4 4
8 6 2 28 20 32 12 12
8 16 6 106 80 156 120 132 48 48
...
CROSSREFS
Cf. A000142.
Sequence in context: A028586 A253179 A300723 * A355335 A292144 A300324
KEYWORD
nonn,tabf
AUTHOR
Christian Stump, Oct 26 2015
EXTENSIONS
More terms from Alois P. Heinz, Oct 26 2015
STATUS
approved