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A264620 Triangle read by rows: T(n,k) (0 <= k <= n) = number of principal ideals generated by an element of rank k in the 3-tonal partition monoid on n elements. 0
1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 2, 1, 1, 0, 1, 2, 2, 1, 1, 1, 1, 2, 3, 2, 1, 1, 0, 1, 2, 3, 3, 2, 1, 1, 0, 1, 2, 3, 4, 3, 2, 1, 1, 1, 1, 2, 4, 4, 4, 3, 2, 1, 1, 0, 1, 2, 3, 5, 5, 4, 3, 2, 1, 1, 0, 1, 2, 3, 5, 6, 5, 4, 3, 2, 1, 1, 1, 1, 2, 4, 5, 6, 7, 5, 4, 3, 2, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,13

LINKS

Table of n, a(n) for n=0..90.

C. Ahmed, P. Martin, V. Mazorchuk, On the number of principal ideals in d-tonal partition monoids, arXiv preprint arXiv:1503.06718 [math.CO], 2015. See Fig. 2.

EXAMPLE

Triangle begins:

1,

0,1,

0,1,1,

1,1,1,1,

0,1,2,1,1,

0,1,2,2,1,1,

1,1,2,3,2,1,1,

0,1,2,3,3,2,1,1,

0,1,2,3,4,3,2,1,1,

1,1,2,4,4,4,3,2,1,1,

0,1,2,3,5,5,4,3,2,1,1,

0,1,2,3,5,6,5,4,3,2,1,1,

1,1,2,4,5,6,7,5,4,3,2,1,1,

...

CROSSREFS

Cf. A028289.

Sequence in context: A244925 A068914 A090824 * A302301 A277264 A259538

Adjacent sequences:  A264617 A264618 A264619 * A264621 A264622 A264623

KEYWORD

nonn,tabl

AUTHOR

N. J. A. Sloane, Nov 30 2015

STATUS

approved

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Last modified June 17 18:57 EDT 2019. Contains 324198 sequences. (Running on oeis4.)