A018931 - cp's OEIS frontend

A018931 The number of permutations of n cards in which 2 is the first card hit and 3 the next hit after 2.

n	a(n)
3	0
4	1
5	2
6	12
7	72
8	480
9	3600
10	30240
11	282240
12	2903040
13	32659200
14	399168000
15	5269017600
16	74724249600
17	1133317785600
18	18307441152000
19	313841848320000
20	5690998849536000
21	108840352997376000
22	2189611807358976000
23	46225138155356160000
24	1021818843434188800000

[0, 1, 2, 12, 72, 480, 3600, 30240, 282240, 2903040, 32659200, 399168000, 5269017600, 74724249600, 1133317785600, 18307441152000, 313841848320000, 5690998849536000, 108840352997376000, 2189611807358976000, 46225138155356160000, 1021818843434188800000]

cp's OEIS Frontend

A018931 The number of permutations of n cards in which 2 is the first card hit and 3 the next hit after 2.

Table of values

List of values