A221727 - OEIS

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A221727 as a simple table

n	a(n)
1	4
2	52
3	540
4	6188
5	71310
6	824144
7	9525048
8	110070012
9	1271809066
10	14694217628
11	169767833676
12	1961352594276
13	22659537510670
14	261784302805272
15	3024367348612856
16	34940131867655732
17	403658398327592910

[4,52,540,6188,71310,824144,9525048,110070012, 1271809066,14694217628,169767833676,1961352594276, 22659537510670,261784302805272,3024367348612856, 34940131867655732,403658398327592910]