keepdates ()
{
    for i in {0..7};
    do
        ((keep[$(date +%Y%m%d -d "-$i day")]++));
    done;
    for i in {0..4};
    do
        ((keep[$(date +%Y%m%d -d "sunday-$((i+1)) week")]++));
    done;
    for i in {0..12};
    do
        DW=$(($(date +%-W)-$(date -d $(date -d "$(date +%Y-%m-15) -$i month" +%Y-%m-01) +%-W)));
        for ((AY=$(date -d "$(date +%Y-%m-15) -$i month" +%Y); AY < $(date +%Y); AY++ ))
        do
            ((DW+=$(date -d $AY-12-31 +%W)));
        done;
        ((keep[$(date +%Y%m%d -d "sunday-$DW weeks")]++));
    done;
    for i in {0..5};
    do
        DW=$(date +%-W);
        for ((AY=$(($(date +%Y)-i)); AY < $(date +%Y); AY++ ))
        do
            ((DW+=$(date -d $AY-12-31 +%W)));
        done;
        ((keep[$(date +%Y%m%d -d "sunday-$DW weeks")]++));
    done;
    echo ${!keep[@]}
}