A025939 - OEIS

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A025939 as a simple table

n	a(n)
0	1
1	20
2	265
3	2960
4	30301
5	295340
6	2795905
7	25996520
8	238988101
9	2181067460
10	19810829545
11	179385327680
12	1620996705901
13	14628147660380
14	131888407103185
15	1188406175868440
16	10704118783463701
17	96387848642218100

[1,20,265,2960,30301,295340,2795905,25996520, 238988101,2181067460,19810829545,179385327680, 1620996705901,14628147660380,131888407103185, 1188406175868440,10704118783463701, 96387848642218100]