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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

%I

%S 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,

%T 212,1053,366,86,18,5,1,1

%N 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).

%e Triangle (with row sums) begins:

%e n=1: 1 1

%e n=2: 1 1

%e n=3: 1 1 2

%e n=4: 3 1 1 5

%e n=5: 4 5 1 1 11

%e n=6: 12 16 5 1 1 35

%e n=7: 25 61 18 5 1 1 111

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

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

%Y The row sums are A343162.

%K nonn,more,tabf

%O 1,5

%A _N. J. A. Sloane_, Apr 19 2021, based on an email from _Don Knuth_

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Last modified November 28 01:24 EST 2021. Contains 349396 sequences. (Running on oeis4.)