A193361 - cp's OEIS frontend

A193361 a(0)=0, a(1)=0; for n>1, a(n) = a(n-1) + (n-3)*a(n-2) + 1.

n	a(n)
0	0
1	0
2	1
3	2
4	4
5	9
6	22
7	59
8	170
9	525
10	1716
11	5917
12	21362
13	80533
14	315516
15	1281913
16	5383622
17	23330405
18	104084736
19	477371217
20	2246811730
21	10839493637
22	53528916508
23	270318789249
24	1394426035918
25	7341439399397
26	39413238225512
27	215607783811041
28	1200938739448842

[0, 0, 1, 2, 4, 9, 22, 59, 170, 525, 1716, 5917, 21362, 80533, 315516, 1281913, 5383622, 23330405, 104084736, 477371217, 2246811730, 10839493637, 53528916508, 270318789249, 1394426035918, 7341439399397, 39413238225512, 215607783811041, 1200938739448842]

cp's OEIS Frontend

A193361 a(0)=0, a(1)=0; for n>1, a(n) = a(n-1) + (n-3)*a(n-2) + 1.

Table of values

List of values