[x3blah]

Improved

   #/bin/sh
   test -s max-PMID||echo 32449615 > max-PMID;read x < max-PMID;h=pubmed.ncbi.nlm.nih.gov;
   test ${#x} -eq 8||rm max-PMID;sed -i "s/[0-9]\{8\}/$x/" $0;
   case $1 in update) mkfifo 1.fifo 2>/dev/null;test -p 1.fifo||exec echo need 1.fifo;
   (grep "<title>PMID .* is not available" < 1.fifo|sed 1q|sed -n 's/<title>PMID //;s/ *//;s/ .*//;wmax-PMID')&
   y=$((x+10000));seq $x $y|sed '$!s|.*|GET /&/ HTTP/1.1\r\nHost: '"$h"'\r\nConnection: keep-alive\r\n\r\n|; 
   $s|.*|GET /&/ HTTP/1.1\r\nHost: '"$h"'\r\nConnection: close\r\n\r\n|'|socat - ssl:$h:443 2>/dev/null|grep -o '<title>[^<]*' >1.fifo;
   ;;"")awk -v min=1 -v max=$((x-1)) 'BEGIN{srand();printf "https://'$h'/" int(min+rand()*(max-min+1)) "/\n"}';esac