A230555 - OEIS

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A230555 as a simple table

n	a(n)
0	1
1	1
2	2
3	4
4	10
5	25
6	66
7	173
8	460
9	1218
10	3240
11	8602
12	22878
13	60794
14	161668
15	429752
16	1142758
17	3038173
18	8078606
19	21479469
20	57113888

[1,1,2,4,10,25,66,173,460,1218,3240,8602,22878, 60794,161668,429752,1142758,3038173,8078606, 21479469,57113888]