Question

3,1,7,3,13,7,21,15,31,31,?,63,57


need explanation​

Answer 1

Answer:

43

Step-by-step explanation:

Take alternate nos.

3+4=7

7+(4+2)=13

13+(6+2)=21

21+(8+2)=31

then by that trick

31+(10+2)=31+12=43

Answer 2

Answer:

43

Step-by-step explanation:

Two parts:-

1,3,7,15,31,63,...

1*2+1=3

3*2+1=7

7*2+1=15

.

.

31*2+1=63

3,7,13,21,31,?,57

3+4=7

7+6=13

13+8=21

21+10=31

31+12=43

43+14=57