A031970 - cp's OEIS frontend

A031970 Tennis ball problem: Balls 1 and 2 are thrown into a room; you throw one on lawn; then balls 3 and 4 are thrown in and you throw any of the 3 balls onto the lawn; then balls 5 and 6 are thrown in and you throw one of the 4 balls onto the lawn; after n turns, consider all possible collections on lawn and add all the values.

n	a(n)
0	0
1	3
2	23
3	131
4	664
5	3166
6	14545
7	65187
8	287060
9	1247690
10	5368670
11	22917198
12	97195968
13	410030812
14	1722027973
15	7204620067
16	30044212828
17	124932768082
18	518215690018
19	2144815618522
20	8859729437488
21	36533517261412
22	150410878895818
23	618371102344846
24	2538971850705064
25	10412490129563556

[0, 3, 23, 131, 664, 3166, 14545, 65187, 287060, 1247690, 5368670, 22917198, 97195968, 410030812, 1722027973, 7204620067, 30044212828, 124932768082, 518215690018, 2144815618522, 8859729437488, 36533517261412, 150410878895818, 618371102344846, 2538971850705064, 10412490129563556]

cp's OEIS Frontend

Table of values

List of values