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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 (list; graph; refs; listen; history; text; internal format)
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

Table of n, a(n) for n=0..60.

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 * A292144 A300324 A298368

Adjacent sequences:  A263785 A263786 A263787 * A263789 A263790 A263791

KEYWORD

nonn,tabf

AUTHOR

Christian Stump, Oct 26 2015

EXTENSIONS

More terms from Alois P. Heinz, Oct 26 2015

STATUS

approved

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Last modified September 25 00:48 EDT 2020. Contains 337333 sequences. (Running on oeis4.)