${\displaystyle \sum _{k=0}^{n}(-1)^{k}}$

37.162.46.235 (talk) 11:00, 4 December 2024 (UTC)[reply]

1 for n even, 0 for n odd. For ${\displaystyle n\to \infty }$see Grandi's series. --Wrongfilter (talk) 11:18, 4 December 2024 (UTC)[reply]

I hope this is not homework. Note that (for finite ${\displaystyle n}$) this is a finite geometric series.  --Lambiam 21:51, 4 December 2024 (UTC)[reply]