A197467 - OEIS

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A197467 as a simple table

n	a(n)
1	4
2	6
3	12
4	25
5	56
6	132
7	320
8	792
9	1976
10	4962
11	12576
12	32140
13	82704
14	214044
15	556576
16	1453210
17	3808592
18	10015134
19	26413468
20	69844263
21	185126524

[4,6,12,25,56,132,320,792,1976,4962,12576,32140, 82704,214044,556576,1453210,3808592,10015134, 26413468,69844263,185126524]