The law of 1, 1, 3,4,7, 1 1 is that the last number is the sum of the first two terms.

2、4=3+ 1; 7=3+4; 1 1=+7+4, the next item should be 1 1+7= 18, and the next item should be11.

Extended data:

The significance of finding the law to fill in the blanks is actually to strengthen the understanding of the general law of sequence. Although it has many solutions, it is mainly to cultivate your ability to find the general law of series and guess the general term of series (that is, the ability to use incomplete induction), so that when you encounter some series that are difficult to find the general term by general methods, you can guess the general term formula of this series quickly and accurately through the first few terms.

Then prove it by mathematical induction or reduction to absurdity or other methods, bypass the front mountain and get its general formula quickly. Therefore, finding the rules to fill in the blanks will still help us to enhance our understanding of some difficulties and characteristic series.