Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.9)
// Compass (v1.0.1)
// ----

@mixin nth-children($n, $m: $n/2)
{
  $selectorlist: null;
  
  @for $i from 1 to $m+1
  {
    $selectorlist: append($selectorlist, unquote("&:nth-child(#{$n}n+#{$i})"), comma);
  }
  
  #{$selectorlist}
  {
    @content;
  }
}

li
{
  @include nth-children(24)
  {
    background: red;
  }
}

SassMeister-output.css

li:nth-child(24n+1), li:nth-child(24n+2), li:nth-child(24n+3), li:nth-child(24n+4), li:nth-child(24n+5), li:nth-child(24n+6), li:nth-child(24n+7), li:nth-child(24n+8), li:nth-child(24n+9), li:nth-child(24n+10), li:nth-child(24n+11), li:nth-child(24n+12) {
  background: red;
}