Calculate days on which Friday the 13th occurs

for y in $(seq 1996 2018); do echo -n "$y -> "; for m in $(seq 1 12); do NDATE=$(date --date "$y-$m-13" +%A); if [ $NDATE == 'Friday' ]; then PRINTME=$(date --date "$y-$m-13" +%B);echo -n "$PRINTME "; fi; done; echo; done
Simply change the years listed in the first seq, and it will print out all the months in that span of years that have Friday the 13ths in them.
Sample Output
2010 -> August 
2011 -> May 
2012 -> January April July 
2013 -> September December 
2014 -> June 
2015 -> February March November 
2016 -> May 
2017 -> January October 
2018 -> April July 

0
2018-06-13 20:11:46

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