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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”).

A000644 as a simple table

na(n)
11
21
33
47
531
6138
7808
84956
933047
10227328
111614793
1211710299
1386495618
14648399937
154923728056

[1,1,3,7,31,138,808,4956,33047,227328,1614793,
 11710299,86495618,648399937,4923728056]