Wilson's Dictionary of Bible Types 
(c) This number is generally taken to denote that which is unfortunate, unhappy, unlucky, tragic and sad. It is interesting to note that the chapters in the Bible numbered thirteen are characterized by something that is unhappy and sad.
See the following:
ge13 - Here we find the first family quarrel, which is certainly a sad event.
Exodus 13:13 This describes the sad ending of either the ass or the lamb.
le13 - What could be more sorrowful than the leper shut out of the camp.
nu13 - The great tragedy of Israel's history came from the evil report of the ten tribes. In verse13the word Sethur means "mystery." The Hebrew letters constituting his name total666 which is the number of the antichrist. Probably this man was the leader of the rebellion of the ten, for the names of all the other leaders had very lovely meanings.
de13 - The punishment of the false prophet or the dreamer is described in this chapter.
jos13 - Here is recorded the death of Balaam, the false prophet.
jud13 - Israel is delivered into the hands of the Philistines.
1sa13 - Saul's sin of presumption lost for him the Kingdom of Israel.
2sa13 - We read here the tragic story of Amon, his sister Tamar, and the murder by Absalom.
1ki13 - The death of the prophet who disobeyed God is described in this chapter.
2ki13 - Israel is delivered into slavery under Hazael, King of Syria.
1ch13 - Uzza is killed by the Lord for touching the ark.
2ch13 - The defeat of the children of Israel by Jeroboam.
ne13 - Nehemiah punished those who broke the sabbath.
job13 - The lament of Job over the persecution of his friends is described with sadness.
ps13 - David described the deep sorrow of his heart because of the troubles internally and externally which constantly beset him.
pr13 - This sad expression is given "hope deferred maketh the heart sick."
jer13 - This prophecy concerns the ultimate destruction of Judah as indicated by the marred, rotten girdle.
eze13 - This records the wrath of God against the prophets of Israel.
ho13 - God describes Himself as a lion, a leopard and as a bear in His judgments against Israel.
mt13 - Here we read of the seed destroyed by the birds, the tares cast into the fire, the bad fish rejected.
mr13 - We read here the terrible record of the great tribulation days when the wrath of God shall be poured out on the earth.
lu13 - Here we read the story of the woman with an infirmity of eighteen years; also the story of the master closing the door against professors who were hypocrites; also the record of Herod, the fox who was to be destroyed by the Lord. We also read of the house of Jerusalem left desolate because they refused to obey God.
ac13 - Elymas, the sorcerer, was cursed with blindness, and the Jews attacked Paul because they hated his message.
ro13 - There is a warning here against resisting the powers of God, and the statement is made that the night is far spent.
1co13 - The sad revelation is made in this chapter that some people are like sounding brass and tinkling symbols. These have no value to God or to man. The Indian said about such a person "Heap big thunder, but no rain."
2co13 - This is a warning to the Christians that Paul will not spare them when he comes if they continue in their disobedience.
Webster's Dictionary 
(1): ( n.) The number greater by one than twelve; the sum of ten and three; thirteen units or objects.
(2): ( a.) One more than twelve; ten and three; as, thirteen ounces or pounds.
(3): ( n.) A symbol representing thirteen units, as 13 or xiii.
King James Dictionary 
Thirteen, a. thur'teen. Ten and three as thirteen times.