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”).

A002427 as a simple table

na(n)
01
11
2-1
31
4-3
55
6-691
735
8-3617
943867
10-1222277
11854513
12-1181820455
1376977927
14-23749461029
158615841276005
16-84802531453387
1790219075042845
18-26315271553053477373
1938089920879940267
20-261082718496449122051
211520097643918070802691

[1,1,-1,1,-3,5,-691,35,-3617,43867,-1222277,
 854513,-1181820455,76977927,-23749461029,
 8615841276005,-84802531453387,90219075042845,
 -26315271553053477373,38089920879940267,
 -261082718496449122051,1520097643918070802691]