Question Number 166697 by Eulerian last updated on 25/Feb/22
![Σ_(n=0) ^∞ (1/((3n)!)) =^? (1/3) [e + ((2cos((3/( 2(√3)))))/( (√e)))]](Q166697.png)
$$\:\underset{\mathrm{n}=\mathrm{0}} {\overset{\infty} {\sum}}\:\frac{\mathrm{1}}{\left(\mathrm{3n}\right)!}\:\overset{?} {=}\:\frac{\mathrm{1}}{\mathrm{3}}\:\left[\mathrm{e}\:+\:\frac{\mathrm{2cos}\left(\frac{\mathrm{3}}{\:\mathrm{2}\sqrt{\mathrm{3}}}\right)}{\:\sqrt{\mathrm{e}}}\right] \\ $$$$\: \\ $$
Commented by MJS_new last updated on 26/Feb/22
$$\mathrm{see}\:\mathrm{question}\:\mathrm{166660} \\ $$