Malik made the number pattern 1, 3, 7, 15 following a rule. The rule is to double the number and add one. Which number would come after 15?

31 because you have to add one and double it

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.