Numbers which count the ways in which it is possible to draw non-intersecting chords between n points on a circle. more
The Motzkin numbers up to 10
15 :
1,
2,
4,
9,
21,
51,
127,
323,
835,
2188,
5798,
15511,
41835,
113634,
310572,
853467,
2356779,
6536382,
18199284,
50852019,
142547559,
400763223,
1129760415,
3192727797,
9043402501,
25669818476,
73007772802,
208023278209,
593742784829,
1697385471211,
4859761676391,
13933569346707,
40002464776083,
114988706524270,
330931069469828,
953467954114363.
Distribution of the remainders when the numbers in this family are divided by n=2, 3,..., 11. (I took into account 100000 values, from 1 to 6.2⋅1047704).
n\r | 0 | 1 |
2 | 33332 | 66668 | 2 |
3 | 96931 | 2046 | 1023 | 3 |
4 | 16666 | 33334 | 16666 | 33334 | 4 |
5 | 10000 | 22474 | 22491 | 22506 | 22529 | 5 |
6 | 32296 | 1364 | 354 | 64635 | 682 | 669 | 6 |
7 | 55270 | 7458 | 7545 | 7545 | 7375 | 7374 | 7433 | 7 |
8 | 0 | 16748 | 8333 | 16700 | 16666 | 16586 | 8333 | 16634 | 8 |
9 | 90019 | 560 | 341 | 2560 | 803 | 340 | 4352 | 683 | 342 | 9 |
10 | 3335 | 14644 | 7080 | 15448 | 8029 | 6665 | 7830 | 15411 | 7058 | 14500 | 10 |
11 | 1819 | 9830 | 9577 | 9766 | 10008 | 9660 | 9961 | 9773 | 9811 | 9820 | 9975 |
A pictorial representation of the table above
Imagine to divide the members of this family by a number n and compute the remainders. Should they be uniformly distributed, each remainder from 0 to n-1 would be obtained in about (1/n)-th of the cases. This outcome is represented by a white square. Reddish (resp. bluish) squares represent remainders which appear more (resp. less) frequently than 1/n.