A072949 - cp's OEIS frontend

A072949 Number of permutations p of {1,2,3,...,n} such that Sum_{k=1..n} abs(k-p(k)) = 2n.

n	a(n)
0	1
1	0
2	0
3	0
4	4
5	24
6	148
7	744
8	3696
9	17640
10	83420
11	390144
12	1817652
13	8438664
14	39117852
15	181136304
16	838372452
17	3879505944
18	17952463180
19	83086702848
20	384626048292
21	1781018204328
22	8249656925564
23	38225193868560
24	177179811427796
25	821544012667704
26	3810648054607212

[1, 0, 0, 0, 4, 24, 148, 744, 3696, 17640, 83420, 390144, 1817652, 8438664, 39117852, 181136304, 838372452, 3879505944, 17952463180, 83086702848, 384626048292, 1781018204328, 8249656925564, 38225193868560, 177179811427796, 821544012667704, 3810648054607212]

cp's OEIS Frontend

A072949 Number of permutations p of {1,2,3,...,n} such that Sum_{k=1..n} abs(k-p(k)) = 2n.

Table of values

List of values