Marinada '25

[lang=hr] Izračunaj $$\sum_{n = 1}^{\infty} \frac{\varphi (n) \cdot 2^n }{2^{2n} - 2^n}.$$ [/lang] [lang=en] Calculate $$\sum_{n = 1}^{\infty} \frac{\varphi (n) \cdot 2^n }{2^{2n} - 2^n}.$$ [/lang]