Intermediate sum Part 2

Relevant wiki: Geometric Progression Sum

Let us consider a general case for $n$ a positive integer as follows:

$\begin{aligned} S_n & = 3 + 3^2 + 3^3 + \cdots + 3^n & \small \color{#3D99F6} \text{A sum of geometric progession} \\ & = \frac {3(3^n-1)}{3-1} = \frac {3^{n+1}-3}2 \end{aligned}$

$\begin{aligned} \implies 2S_n + 3 & = 2\times \frac {3^{n+1}-3}2 + 3 = \color{#3D99F6} \boxed{3^{n+1}} \ \blacksquare & \small \color{#3D99F6} \text{A power of 3} \end{aligned}$

$\begin{array}{cccc} S=3+3^2+3^3+3^4+3^5+3^6+\dots+3^{2018} \\ -3S=3^2+3^3+3^4+3^5+3^6+\dots+3^{2019}\\ \hline -2S=3-3^{2019} \end{array}$

$-2S=3-3^{2019} \implies 2S=3^{2019}-3 \implies 2S+3=3^{2019}$

So the answer is Yes