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A117428 as a simple table

n a(n)
0 1
1 3
2 9
3 30
4 110
5 442
6 1908
7 8822
8 43330
9 224595
10 1221860
11 6953514
12 41232563
13 253992215
14 1620599471
15 10689986451
16 72734177909
17 509288018981
18 3663185604591
19 27027424720210
20 204246277508032
21 1578970198567932

[1,3,9,30,110,442,1908,8822,43330,224595,1221860,
 6953514,41232563,253992215,1620599471,10689986451,
 72734177909,509288018981,3663185604591,
 27027424720210,204246277508032,1578970198567932]

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Last modified December 12 18:24 EST 2018. Contains 318081 sequences. (Running on oeis4.)