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A295390 Number T(n,k) of permutations of [n] having exactly k consecutive 3-term arithmetic progressions; triangle T(n,k), n>=0, 0<=k<=max(n-2,0), read by rows. 3
1, 1, 2, 4, 2, 18, 4, 2, 80, 34, 4, 2, 482, 196, 36, 4, 2, 3280, 1418, 292, 44, 4, 2, 26244, 11292, 2426, 304, 48, 4, 2, 231148, 106132, 22156, 3010, 372, 56, 4, 2, 2320130, 1046176, 225804, 32308, 3892, 424, 60, 4, 2, 25238348, 11679626, 2585080, 366484, 42176, 4540, 472, 68, 4, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Alois P. Heinz, Rows n = 0..18, flattened

EXAMPLE

Triangle T(n,k) begins:

:       1;

:       1;

:       2;

:       4,       2;

:      18,       4,      2;

:      80,      34,      4,     2;

:     482,     196,     36,     4,    2;

:    3280,    1418,    292,    44,    4,   2;

:   26244,   11292,   2426,   304,   48,   4,  2;

:  231148,  106132,  22156,  3010,  372,  56,  4, 2;

: 2320130, 1046176, 225804, 32308, 3892, 424, 60, 4, 2;

CROSSREFS

Column k=0 gives A295370.

Row sums give A000142.

Cf. A162982, A289207.

Sequence in context: A186526 A227924 A100944 * A059890 A295640 A210457

Adjacent sequences:  A295387 A295388 A295389 * A295391 A295392 A295393

KEYWORD

nonn,tabf

AUTHOR

Alois P. Heinz, Nov 21 2017

STATUS

approved

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Last modified March 21 04:59 EDT 2019. Contains 321364 sequences. (Running on oeis4.)