user23428: I ran Stockfish 2 times with the command go depth 1.
First time
info depth 1 seldepth 1 multipv 1 score cp 114 nodes 20 nps 10000 tbhits 0 time 2 pv e2e3

Second time:
info depth 1 seldepth 1 multipv 1 score cp 105 nodes 22 nps 22000 tbhits 0 time 1 pv e2e4

Why does the number of nodes increase from 20 to 22?

user12873: It's likely due to Stockfish's transposition table (essentially a fast lookup table that Stockfish can use to refer back to positions it evaluated before). During your first run, information about visited positions was stored in the table. Then on the second run, Stockfish may have looked at some of Black's moves after depth 1 (since it's already evaluated all states at depth 1).
SmallChess' answer to this question may be useful if it's still confusing:
How to read score from stockfish - inconsistent response every call?
Edit: to test if it is the transposition table behind this, try to reset it after the first run (close the whole program if you can't figure out how). Then on the second run, the number of nodes should be the same (as well as the centipawn evaluation).

23428: <p>I ran Stockfish 2 times with the command <code>go depth 1</code>.</p>

<p>First time</p>

<pre><code>info depth 1 seldepth 1 multipv 1 score cp 114 nodes 20 nps 10000 tbhits 0 time 2 pv e2e3
</code></pre>

<p>Second time:</p>

<pre><code>info depth 1 seldepth 1 multipv 1 score cp 105 nodes 22 nps 22000 tbhits 0 time 1 pv e2e4
</code></pre>

<p>Why does the number of nodes increase from 20 to 22?</p>
 12873: <p>It's likely due to Stockfish's transposition table (essentially a fast lookup table that Stockfish can use to refer back to positions it evaluated before). During your first run, information about visited positions was stored in the table. Then on the second run, Stockfish may have looked at some of Black's moves after depth 1 (since it's already evaluated all states at depth 1).</p>

<p>SmallChess' answer to this question may be useful if it's still confusing:</p>

<p><a href="https://chess.stackexchange.com/questions/14021/how-to-read-score-from-stockfish-inconsistent-response-every-call">How to read score from stockfish - inconsistent response every call?</a></p>

<p>Edit: to test if it is the transposition table behind this, try to reset it after the first run (close the whole program if you can't figure out how). Then on the second run, the number of nodes should be the same (as well as the centipawn evaluation).</p>
