A375222 - cp's OEIS frontend

A375222 a(n) is the number of permutations of the multiset 1,1, 2,2, ..., n,n such that exactly one pair k,k stays at its initial locations 2k-1, 2k.

n	a(n)
1	1
2	0
3	15
4	296
5	10965
6	609864
7	47880595
8	5047886640
9	688359502089
10	117929734950320
11	24798753695076471
12	6280419381186155160
13	1885582606127524251805
14	662239984799385248609976
15	268999138538324585872798395
16	125133475474486312764311243744
17	66091677106419135401506827779985

[1, 0, 15, 296, 10965, 609864, 47880595, 5047886640, 688359502089, 117929734950320, 24798753695076471, 6280419381186155160, 1885582606127524251805, 662239984799385248609976, 268999138538324585872798395, 125133475474486312764311243744, 66091677106419135401506827779985]

cp's OEIS Frontend

A375222 a(n) is the number of permutations of the multiset 1,1, 2,2, ..., n,n such that exactly one pair k,k stays at its initial locations 2k-1, 2k.

Table of values

List of values