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A294432 Triangle read by rows: T(n,k) (0 <= k <= n) is the rank of the ideal I_r in the inverse semigroup D_n of all difunctional relations on an n-element set. 1
1, 1, 2, 1, 3, 3, 1, 7, 8, 8, 1, 15, 27, 21, 19, 1, 31, 92, 84, 60, 57, 1, 63, 303, 385, 266, 213, 209, 1, 127, 968, 1768, 1419, 986, 889, 884, 1, 255, 3027, 7901, 8049, 5446, 4313, 4154, 4148, 1, 511, 9332, 34364, 45810, 33883, 23888, 21405, 21163, 21156, 1, 1023, 28503, 146265, 256576, 223439, 150465, 121186, 116342, 115993, 115985 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..65.

James East, A. Vernitski, Ranks of ideals in inverse semigroups of difunctional binary relations, arXiv preprint arXiv:1612.04935 [math.GR], 2016.

J. East and A. Vernitski, Ranks of ideals in inverse semigroups of difunctional binary relations, Semigroup Forum (to appear).

EXAMPLE

Triangle begins:

1,

1,2,

1,3,3,

1,7,8,8,

1,15,27,21,19,

1,31,92,84,60,57,

1,63,303,385,266,213,209,

1,127,968,1768,1419,986,889,884,

1,255,3027,7901,8049,5446,4313,4154,4148,

1,511,9332,34364,45810,33883,23888,21405,21163,21156,

1,1023,28503,146265,256576,223439,150465,121186,116342,115993,115985,

...

CROSSREFS

See A294431 for the final diagonal.

Sequence in context: A271238 A186740 A103525 * A121436 A330694 A088074

Adjacent sequences:  A294429 A294430 A294431 * A294433 A294434 A294435

KEYWORD

nonn,tabl

AUTHOR

N. J. A. Sloane, Nov 13 2017

STATUS

approved

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Last modified August 12 17:17 EDT 2020. Contains 336439 sequences. (Running on oeis4.)