Haryana Police Constable Model Paper 3

Given:
The series is 3, 7, 13, 21, 31, ?, 57
Calculation:
The series is square of Natural numbers starting from 1 with addition of next natural number in it.
$1^2+2=3$
$2^2+3=7$
$3^2+4=13$
$4^2+5=21$
$5^2+6=31$
$6^2+7=43$
$7^2+8=57$
∴ For missing term which is the $6^{\mathrm{th}}$ term it will be 43.