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A216716 Triangle read by rows: number of permutations of [1..n] with k progressions of rise 2, distance 1 and length 3 (n >= 1, k >= 0). 6
1, 2, 6, 24, 114, 6, 674, 44, 2, 4714, 294, 30, 2, 37754, 2272, 276, 16, 2, 340404, 20006, 2236, 216, 16, 2, 3412176, 193896, 20354, 2200, 156, 16, 2, 37631268, 2056012, 206696, 20738, 1908, 160, 16, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..39.

K. J. Parsons, Arithmetic progressions in permutations, Thesis, Washington and Lee University, 2011

Wayne M. Dymacek, Isaac Lambert and Kyle Parsons, Arithmetic Progressions in Permutations, 2012.

EXAMPLE

Triangle begins:

1

2

6 [this is for n=3]

24

114 6

674 44 2

4714 294 30 2

37754 2272 276 16 2

340404 20006 2236 216 16 2

3412176 193896 20354 2200 156 16 2

37631268 2056012 206696 20738 1908 160 16 2

...

CROSSREFS

Cf. A216717.

Sequence in context: A152328 A152325 A152329 * A192088 A245233 A228907

Adjacent sequences:  A216713 A216714 A216715 * A216717 A216718 A216719

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Sep 15 2012

STATUS

approved

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Last modified September 15 18:22 EDT 2019. Contains 327082 sequences. (Running on oeis4.)