Question

What is the missing number 1,3,10,21,64,129 ? 777

Answer 1

Answer:

388

Step-by-step explanation:

n1 = 1

n2 = 3

n3 = 10

n4 = 21

n5 = 64

n6 = 129

n7 = ?

n8 = 777

It follows the pattern,

(2n + 1), (3n + 1), (2n + 1), (3n + 1), and so on..

where, n is the previous number

n1 = 1

n2 = 2(n1) + 1 = 3

n3 = 3(n2) + 1 = 10

n4 = 2(n3) + 1 = 21

n5 = 3(n4) + 1 = 64

n6 = 2(n5) + 1 = 129

n7 = 3(n6) + 1 = 388

n8 = 2(n7) + 1 = 777