what is the next number? 3 4 6 9 13 18 24

so 3+x=43+1=44+x=64+2=6notice the patern3+1=44+2=66+3=99+4=1313+5=1818+6=24so then next + must be 724+7=31

3  4   6  9  13  18  24If you watch carefully, between the first two numbers  1 was added.Then 2 was added to 4 to have 6.3 added to 6 to give  9.4 added to 9 to result to 13.5 added to 13 to give 18.6 added to 18 to give 24.Therefore 7 would be added to 24 to give:  24 + 7 = 31.So it is 31. Cheers.