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, 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

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: A186740 A353585 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