Explanation:-
Natural number starts with 1,2,3,4,5,6……….
This series is derived by adding 2 consecutive odd Natural Numbers and even natural numbers

first 2 odd natural numbers are 1 and 3 = i.e. square of 1 + square of 3 = gives 10 ( first number)
first 2 even natural numbers are 2 and 4 = Square of 2 + square of 4 = gives 20 ( second number)
second 2 odd natural numbers are 5 and 7 = gives 74 (third number)
second 2 even natural numbers are 6 and 8 = gives 100 ( fourth number)
third 2 odd natural numbers are 9 and 11 which gives 202 ( 5 th number)

Answered by : Vishal Vinchankar