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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”).

A027881 as a simple table

na(n)
11
21
32
44
59
620
751
8121
9321
10826
112186
125789
1316114
1442449
15118281
16328425
17908933
182510553
197138324
2019869748

[1,1,2,4,9,20,51,121,321,826,2186,5789,16114,
 42449,118281,328425,908933,2510553,7138324,
 19869748]