How many 4s are there in the following number sequence which are immediately preceded by 6 and immediately followed by 5?

4 6 5 9 4 6 4 5 1 3 5 4 6 2 3 1 6 4 5 8 9

We need to find $4$s that have a $6$ directly before it and a $5$ directly after it.

We're looking for this exact pattern: $6$-$4$-$5$

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Here's the number sequence:

$4, 6, 5, 9, 4, 6, 4, 5, 1, 3, 5, 4, 6, 2, 3, 1, 6, 4, 5, 8, 9$

Let me check every time I see a $4$ and examine its neighbors:

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Position 1: $4, 6, 5...$

Before $4$: Nothing (it's the first number)

Doesn't count

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Position 5: $...9, 4, 6...$

Before $4$: $9$ (not $6$)

After $4$: $6$ (not $5$)

Doesn't count

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Position 7: $...6, 4, 5...$

Before $4$: $6$ ✓

After $4$: $5$ ✓

This counts! (Pattern: $6$-$4$-$5$)

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Position 12: $...5, 4, 6...$

Before $4$: $5$ (not $6$)

After $4$: $6$ (not $5$)

Doesn't count

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Position 18: $...6, 4, 5...$

Before $4$: $6$ ✓

After $4$: $5$ ✓

This counts! (Pattern: $6$-$4$-$5$)

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Let me highlight the patterns we found:

$4, 6, 5, 9, 4, [6, 4, 5], 1, 3, 5, 4, 6, 2, 3, 1, [6, 4, 5], 8, 9$

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There are $2$ fours that are immediately preceded by $6$ and immediately followed by $5$.

Answer: $2$