A072948 - cp's OEIS frontend

A072948 Number of permutations p of {1,2,3,...,2n} such that Sum_{k=1..2n} abs(k-p(k)) = 2n.

n	a(n)
0	1
1	1
2	7
3	46
4	327
5	2350
6	17222
7	127508
8	952299
9	7159090
10	54107670
11	410729140
12	3129241874
13	23914923644
14	183254996828
15	1407497158968
16	10832287881639
17	83516348514010
18	644935028526278
19	4987483388201684
20	38619491922881310
21	299390833303838980
22	2323441087636417604

[1, 1, 7, 46, 327, 2350, 17222, 127508, 952299, 7159090, 54107670, 410729140, 3129241874, 23914923644, 183254996828, 1407497158968, 10832287881639, 83516348514010, 644935028526278, 4987483388201684, 38619491922881310, 299390833303838980, 2323441087636417604]

cp's OEIS Frontend

A072948 Number of permutations p of {1,2,3,...,2n} such that Sum_{k=1..2n} abs(k-p(k)) = 2n.

Table of values

List of values