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A343168 Irregular triangle read by rows: T(n,k) (n>=1, 2 <= k <= n for n >= 2) gives number of graphs on n nodes that are isometrically embeddable into the Hamming graph H(n,k). 6
1, 1, 1, 1, 3, 1, 1, 4, 5, 1, 1, 12, 16, 5, 1, 1, 25, 61, 18, 5, 1, 1, 79, 239, 84, 18, 5, 1, 1, 212, 1053, 366, 86, 18, 5, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..37.

EXAMPLE

Triangle (with row sums) begins:

  n=1:    1                                                     1

  n=2:    1                                                     1

  n=3:    1     1                                               2

  n=4:    3     1     1                                         5

  n=5:    4     5     1     1                                  11

  n=6:   12    16     5     1     1                            35

  n=7:   25    61    18     5     1     1                     111

  n=8:   79   239    84    18     5     1     1               427

CROSSREFS

See A343163-A343167 for the first three columns and their sums.

The row sums are A343162.

Sequence in context: A321876 A131238 A133380 * A105687 A209415 A058879

Adjacent sequences:  A343165 A343166 A343167 * A343169 A343170 A343171

KEYWORD

nonn,more,tabf

AUTHOR

N. J. A. Sloane, Apr 19 2021, based on an email from Don Knuth

STATUS

approved

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Last modified October 27 20:04 EDT 2021. Contains 348289 sequences. (Running on oeis4.)