login

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”).

A198021 as a simple table

na(n)
11
25
320
4278
54448
6175624
712844710
81595718051
9427062500640

[1,5,20,278,4448,175624,12844710,1595718051,
 427062500640]