A197460 - OEIS

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A197460 as a simple table

n	a(n)
1	1
2	1
3	4
4	6
5	19
6	49
7	143
8	403
9	1235
10	3681
11	11354
12	34944
13	108956
14	340635
15	1072593
16	3388161
17	10751029
18	34217608
19	109255023
20	349750874
21	1122436127
22	3610017340

[1,1,4,6,19,49,143,403,1235,3681,11354,34944, 108956,340635,1072593,3388161,10751029,34217608, 109255023,349750874,1122436127,3610017340]