A273653 - cp's OEIS frontend

A273653 Number of forests of labeled rooted trees of height at most 1, with n labels, three of which are used for root nodes and any root may contain >= 1 labels.

n	a(n)
3	5
4	40
5	220
6	1040
7	4550
8	19040
9	77448
10	308640
11	1209450
12	4668400
13	17766892
14	66718288
15	247397150
16	906584000
17	3285842960
18	11788924992
19	41902786770
20	147668053200
21	516315206260
22	1792304871280
23	6180666260230
24	21184488791840
25	72205377800600
26	244837696095200

[5, 40, 220, 1040, 4550, 19040, 77448, 308640, 1209450, 4668400, 17766892, 66718288, 247397150, 906584000, 3285842960, 11788924992, 41902786770, 147668053200, 516315206260, 1792304871280, 6180666260230, 21184488791840, 72205377800600, 244837696095200]

cp's OEIS Frontend

A273653 Number of forests of labeled rooted trees of height at most 1, with n labels, three of which are used for root nodes and any root may contain >= 1 labels.

Table of values

List of values