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A007122 as a simple table

na(n)
10
20
30
40
50
62
74
815
936
10108
11276
12770
132036
145586
1515072
1641370
17113184
18312488
19863824
202401344
216692368
2218724990
2352531788
24147824963
25417006316
261179285900
273342274092
289492427854
2927011049612
3076999988534

[0,0,0,0,0,2,4,15,36,108,276,770,2036,5586,15072,
 41370,113184,312488,863824,2401344,6692368,
 18724990,52531788,147824963,417006316,1179285900,
 3342274092,9492427854,27011049612,76999988534]