It’s actually a bit simpler; no need to fill in the gaps.
layouts/posts/list.html
{{ define "main" }}
<h1>{{ .Title }}</h1>
{{ .Content }}
{{/* Set constants. */}}
{{ $numFeaturedPages := 2 }}
{{ $numPagesFirstPager := 10 }}
{{ $numPagesSubsequentPagers := 4 }}
{{/* Paginate the page collection excluding the extra pages on the first pager. */}}
{{ $paginator := .Paginate (.Pages | after (sub $numPagesFirstPager $numPagesSubsequentPagers)) $numPagesSubsequentPagers }}
{{/* Featured pages. */}}
{{ if eq $paginator.PageNumber 1 }}
<pre>// BEGIN FEATURED</pre>
{{ range first $numFeaturedPages .Pages }}
<h3><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></h3>
{{ end }}
<pre>// END FEATURED</pre>
{{ end }}
{{/* Extra pages for the first pagter. */}}
{{ if eq $paginator.PageNumber 1 }}
<pre>// BEGIN EXTRA</pre>
{{ range .Pages | after $numFeaturedPages | first (sub $numPagesFirstPager $numPagesSubsequentPagers $numFeaturedPages) }}
<h3><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></h3>
{{ end }}
<pre>// END EXTRA</pre>
{{ end }}
{{/* The paginated page collection. */}}
<pre>// BEGIN THE REST FOR THIS PAGER</pre>
{{ range $paginator.Pages }}
<h3><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></h3>
{{ end }}
<pre>// END THE REST FOR THIS PAGER</pre>
{{/* Navigation. */}}
{{ template "_internal/pagination.html" . }}
{{ end }}
But the OP’s goal is still not entirely clear to me.