http://magazine.pomona.edu/pomoniana/2015/02/13/the-mystery-of-47/

test_47.sh

#!/usr/local/bin/bash
  
# a million random digits with 100,000 normal deviates
[ -f digits.txt ] || (
    wget https://www.rand.org/content/dam/rand/pubs/monograph_reports/MR1418/MR1418.digits.txt.zip && 
    unzip MR1418.digits.txt.zip) 

rando=$( cat digits.txt | cut --complement -f1 -d' ' | xargs | sed 's/ *//g' )

for n in {00..99}; do
    echo -e "$n\t$( grep -o $n <<< $rando | wc -l )" # num    occurences
done | sort -n -k2,2 --reverse | grep -n --color ^47