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Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A146790 as a simple table

na(n)
11
21
31
41
55
617
767
8311
91473
107613
1168761
12661093
138801627
14124939017
152484498069
1653077957657

[1,1,1,1,5,17,67,311,1473,7613,68761,661093,
 8801627,124939017,2484498069,53077957657]