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A271617 T(n,k) = Number of ways to reciprocally link elements of an n X n X n triangular array with themselves or a neighbor, with no more than k elements linked to themselves. 9
1, 1, 3, 1, 3, 2, 1, 4, 17, 6, 1, 4, 17, 114, 240, 1, 4, 26, 114, 240, 2238, 1, 4, 26, 307, 2571, 2238, 2196, 1, 4, 27, 307, 2571, 42702, 216318, 37004, 1, 4, 27, 406, 7764, 42702, 216318, 5622392, 20454036, 1, 4, 27, 406, 7764, 222936, 3243689, 5622392, 20454036, 970623228 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Table starts

........1........1..........1..........1...........1...........1............1

........3........3..........4..........4...........4...........4............4

........2.......17.........17.........26..........26..........27...........27

........6......114........114........307.........307.........406..........406

......240......240.......2571.......2571........7764........7764........12180

.....2238.....2238......42702......42702......222936......222936.......550173

.....2196...216318.....216318....3243689.....3243689....18314708.....18314708

....37004..5622392....5622392..132728354...132728354..1182352612...1182352612

.20454036.20454036.1491326272.1491326272.30892003921.30892003921.291282493174

LINKS

Alois P. Heinz, Antidiagonals n = 1..20, flattened (first 16 antidiagonals from R. H. Hardin)

EXAMPLE

Some solutions for n=4 k=4

.....5........5........0........5........0........6........5........5

....2.0......2.0......0.5......2.0......6.0......5.1......2.0......2.6

...6.6.6....0.5.5....5.2.5....0.0.0....0.1.6....2.0.0....5.4.3....5.5.1

..0.1.1.1..0.2.2.0..2.0.2.0..4.3.4.3..0.4.3.1..0.4.3.0..2.0.4.3..2.2.4.3

Element moves: 0=itself 1=nw 2=ne 3=w 4=e 5=sw 6=se, reciprocals total 7

CROSSREFS

Sequence in context: A047787 A102668 A243848 * A057741 A133571 A326420

Adjacent sequences:  A271614 A271615 A271616 * A271618 A271619 A271620

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin, Apr 10 2016

STATUS

approved

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Last modified June 19 03:31 EDT 2021. Contains 345125 sequences. (Running on oeis4.)