A263420 - OEIS

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A263420 as a simple table

n	a(n)
1	1
2	4
3	36
4	196
5	961
6	5329
7	29584
8	160000
9	868624
10	4739329
11	25816561
12	140517316
13	765186244
14	4167218916
15	22692108321
16	123567013441
17	672885527616
18	3664192267264
19	19953231345216
20	108654793385121
21	591677262389889

[1,4,36,196,961,5329,29584,160000,868624,4739329, 25816561,140517316,765186244,4167218916, 22692108321,123567013441,672885527616, 3664192267264,19953231345216,108654793385121, 591677262389889]