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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”).

A146857 as a simple table

na(n)
11
21
31
41
51
61
71
81
917
1017
1149
1249
13249
14249
153481
163481
1780333
1880333
191943801
201943801
2159816323
2259816323

[1,1,1,1,1,1,1,1,17,17,49,49,249,249,3481,3481,
 80333,80333,1943801,1943801,59816323,59816323]