Hi, normally, it is recommended to update the BIOS and iDRAC sequentially without a direct jump in large jumps. But as far as I can see there is not a huge jump with the latest version. I think you can update directly. However, if you want, you can update to 2.16.1 first and then the latest version.
I Have PowerEdge MX740C I want to upgrade Bios firmware, but i'm confused that can i jump to 2.14.2 to 2.18.1 firmware. Or we can follow firmware sequence Currant Bios firmware version is 2.14.2 Available Version is 2.18.1 
it is possible to jump 2.14.2 bios firmware to 2.18.1 in dell PowerEdge MX740C