A155404 - OEIS

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A155404 as a simple table

n	a(n)
4	1
5	4
6	10
7	22
8	40
9	135
10	446
11	2376
12	12035
13	65714
14	364923
15	2734456
16	23495580
17	245925457
18	2738475904
19	35447846068
20	514467522739

[1,4,10,22,40,135,446,2376,12035,65714,364923, 2734456,23495580,245925457,2738475904,35447846068, 514467522739]