A181939 - cp's OEIS frontend

A181939 Number of pairs of set partitions of {1,2,...,n} whose meet is {{1},{2},...,{n}} and join is {{1,2,...,n}}.

n	a(n)
0	1
1	1
2	2
3	8
4	56
5	552
6	7202
7	118456
8	2369922
9	56230544
10	1552048082
11	49080888144
12	1756527398738
13	70427165428648
14	3136819046716266
15	154090456510590632
16	8296738497931578818
17	487014208107376581984
18	31018372994440588508642
19	2134584265273475942046304

[1, 1, 2, 8, 56, 552, 7202, 118456, 2369922, 56230544, 1552048082, 49080888144, 1756527398738, 70427165428648, 3136819046716266, 154090456510590632, 8296738497931578818, 487014208107376581984, 31018372994440588508642, 2134584265273475942046304]

cp's OEIS Frontend

A181939 Number of pairs of set partitions of {1,2,...,n} whose meet is {{1},{2},...,{n}} and join is {{1,2,...,n}}.

Table of values

List of values