ccoakley stubbscroll .
stubbscroll , 9!= 362880 :
( ) .
0 1 2 3 --> 0
0 1 3 2 --> 1
0 2 1 3 --> 2
...
1 0 2 3 --> 6
1 0 3 2 --> 7
...
3 1 2 0 --> 21
3 2 0 1 --> 22
3 2 1 0 --> 23
,
n = a_1 * 1! + a_2 * 2! + a_3 * 3! + a_4 * 4! + ...
0 <= a_k <= k. s, 0 s! -1, s-1 n, (a_1,a_2,...,a_(s-1)). n :
for i = 1 to s-1
the i-th symbol becomes the (a_(s-i)+1)-th smallest unused symbol
the last symbol is the left over one
, . , 4231 {1,2,3,4,5,6,7,8}. 4231
4231 = 1 + 2*2115 : a_1 = 1
2115 = 0 + 3* 705 : a_2 = 0
705 = 1 + 4* 176 : a_3 = 1
176 = 1 + 5* 35 : a_4 = 1
35 = 5 + 6* 5 : a_5 = 5
5 = 5 + 7* 0 : a_6 = 5
( a_7) 0. a_i (a_7, a_6,... a_1),
coefficients symbols choice
0,5,5,1,1,0,1 1,2,3,4,5,6,7,8 1
5,5,1,1,0,1 2,3,4,5,6,7,8 7
5,1,1,0,1 2,3,4,5,6,8 8
1,1,0,1 2,3,4,5,6 3
1,0,1 2,4,5,6 4
0,1 2,5,6 2
1 5,6 6
- 5 5
: 17834265.
246351:
symbols count perm index(head)
1,2,3,4,5,6 6 2,4,6,3,5,1 1 a_5 = 1
1,3,4,5,6 5 4,6,3,5,1 2 a_4 = 2
1,3,5,6 4 6,3,5,1 3 a_3 = 3
1,3,5 3 3,5,1 1 a_2 = 1
1,5 2 5,1 1 a_1 = 1
index - `1 * 5! + 2 * 4! + 3 * 3! + 1 * 2! + 1 * 1!= 187.
, . (O (s ^ 2)), ( ?). , , .
, .
, , , . ( ) 9!/2 = 181440 . . , , a_k .
, . , . , , - . .
, 5 . 8 , 8!/2 = 20160 . ( .)
, , , , .
, , , .
, , .