Index.php not found in permalinks

Hello,

The pagination on my home page (http://www.writechoice.co.in/writechoice) is generating the following urls:

http://www.writechoice.co.in/writechoice/page/2/
http://www.writechoice.co.in/writechoice/page/3/
http://www.writechoice.co.in/writechoice/page/4/

This URLs ares not working.

But when I am adding index.php to this, it is working

http://www.writechoice.co.in/writechoice/index.php/page/2/
http://www.writechoice.co.in/writechoice/index.php/page/3/
http://www.writechoice.co.in/writechoice/index.php/page/4/

Could someone please help with the issue?