The rule of 1, 1, 2,4,7,13,24 is that the sum of the first three numbers is equal to the fourth number. That is, 1+ 1+2 = 4,1+2+4 = 7,2+4+7 =13,4+7+13 = 24. Mathematical method is to express the state, relationship and process of things in mathematical language, and to deduce, calculate and analyze them, thus forming a method of explaining, judging and predicting problems.

Extended data:

Basic mathematical methods commonly used in middle school mathematics can be roughly divided into the following three categories:

Methods in (1) logic. For example, analysis (including reduction to absurdity), synthesis, reduction to absurdity, induction and exhaustion. These methods should not only abide by the basic laws and rules in logic, but also have mathematical characteristics because they are used in mathematics.

(2) General methods in mathematics, such as modeling method, elimination method, reduction method, substitution method, image method, comparison method and scale method, as well as vector method and mathematical induction to be studied in the future (different from incomplete induction in logic). These methods are extremely important and widely used.

(3) Special methods in mathematics. For example, collocation method, undetermined coefficient method, elimination method, formula method, substitution method, sub-item supplement method and so on.

References:

Baidu Encyclopedia-Mathematical Methods