A204108 - OEIS

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A204108 as a simple table

n	a(n)
0	1
1	4
2	56
3	428
4	2741
5	13247
6	52059
7	167502
8	453377
9	1047750
10	2112634
11	3808004
12	6369041
13	10436597
14	18107008
15	36365073
16	90462493
17	282733629
18	1074838721
19	4716194782
20	22663033612
21	114269420056
22	586835167740

[1,4,56,428,2741,13247,52059,167502,453377, 1047750,2112634,3808004,6369041,10436597,18107008, 36365073,90462493,282733629,1074838721,4716194782, 22663033612,114269420056,586835167740]