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A273904 as a simple table

na(n)
20
31
44
513
644
7149
8498
91656
105498
1118236
1260456
13200409
14664464
152203755
167311894
1724271290
1880605250
19267821525
20890305418
212961015981
229852481830
2332798011430
24109229396466
25363927233758
261213012655490
274044684629394
2813491663770344

[0,1,4,13,44,149,498,1656,5498,18236,60456,200409,
 664464,2203755,7311894,24271290,80605250,
 267821525,890305418,2961015981,9852481830,
 32798011430,109229396466,363927233758,
 1213012655490,4044684629394,13491663770344]