A309053 - cp's OEIS frontend

A309053 Triangular array T read by rows: T(r,c) is the number of double permutations of the integers from 1 to r which have exactly c different values visible when viewed from the left, in the sense that a higher number hides a lower one.

n	a(n)
0	1
1	0
2	1
3	0
4	1
5	3
6	0
7	4
8	17
9	15
10	0
11	36
12	181
13	254
14	105
15	0
16	576
17	3220
18	5693
19	3966
20	945
21	0
22	14400
23	86836
24	177745
25	161773
26	67251
27	10395
28	0
29	518400
30	3313296
31	7527688
32	8134513
33	4524085
34	1248483
35	135135

[1, 0, 1, 0, 1, 3, 0, 4, 17, 15, 0, 36, 181, 254, 105, 0, 576, 3220, 5693, 3966, 945, 0, 14400, 86836, 177745, 161773, 67251, 10395, 0, 518400, 3313296, 7527688, 8134513, 4524085, 1248483, 135135]

cp's OEIS Frontend

A309053 Triangular array T read by rows: T(r,c) is the number of double permutations of the integers from 1 to r which have exactly c different values visible when viewed from the left, in the sense that a higher number hides a lower one.

Table of values

List of values