A067534 - OEIS

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A067534 as a simple table

n	a(n)
1	1
2	20
3	161
4	900
5	4225
6	18196
7	75185
8	304836
9	1225905
10	4913620
11	19669121
12	78697220
13	314817441
14	1259308180
15	5037283345
16	20149198916
17	80596879185
18	322387621716
19	1289550617185
20	5158202628740
21	20632810709441

[1,20,161,900,4225,18196,75185,304836,1225905, 4913620,19669121,78697220,314817441,1259308180, 5037283345,20149198916,80596879185,322387621716, 1289550617185,5158202628740,20632810709441]