A009723 - OEIS

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A009723 as a simple table

n	a(n)
0	1
1	3
2	57
3	1995
4	128881
5	12775059
6	1796958633
7	342118793307
8	84276974508769
9	26141579246291235
10	9956883572644073241
11	4570240365824839488747
12	2487549038143714062879313
13	1584207614996350912703688627

[1,3,57,1995,128881,12775059,1796958633, 342118793307,84276974508769,26141579246291235, 9956883572644073241,4570240365824839488747, 2487549038143714062879313, 1584207614996350912703688627]