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A047131 as a simple table

na(n)
01
12
23
36
410
520
635
770
8140
9252
10504
11932
121864
133493
146986
1513972
1626265
1752530
18100168
19200336
20384573
21769146
221538292
232950530
245901060
2511422700
2622845400
2744403564
2888807128
29177614256
30344644881
31689289762
321346117062

[1,2,3,6,10,20,35,70,140,252,504,932,1864,3493,
 6986,13972,26265,52530,100168,200336,384573,
 769146,1538292,2950530,5901060,11422700,22845400,
 44403564,88807128,177614256,344644881,689289762,
 1346117062]