A136580 - OEIS

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A136580 as a simple table

n	a(n)
0	1
1	1
2	3
3	7
4	27
5	127
6	747
7	5167
8	41067
9	368047
10	3669867
11	40284847
12	482671467
13	6267305647
14	87660962667
15	1313941673647
16	21010450850667
17	357001369769647
18	6423384156578667
19	122002101778601647
20	2439325392333218667

[1,1,3,7,27,127,747,5167,41067,368047,3669867, 40284847,482671467,6267305647,87660962667, 1313941673647,21010450850667,357001369769647, 6423384156578667,122002101778601647, 2439325392333218667]