SELECT DISTINCT(Num) AS ConsecutiveNums

FROM (

SELECT

Num,

@counter := IF(@prev = Num, @counter + 1, 1) AS how_many_cnt_in_a_row,

@prev := Num

FROM Logs y, (SELECT @counter:=1, @prev:=NULL) vars

) sq

WHERE how_many_cnt_in_a_row >= 3

SELECT DISTINCT l1.Num as ConsecutiveNums

FROM Logs l1, Logs l2, Logs l3

WHERE l1.Id + 1 = l2.Id AND l2.Id + 1 = l3.Id AND l1.Num = l2.Num AND l2.Num = l3.Num