Discrete mathematics has been requested a great many times, but no such course has been created as of yet.  Discrete mathematics is generally the third computer science course in a university program; it's pretty core.  It's also critical for circuit theory and other computer engineering topics.  This is one of the most important STEM courses in digital electronic engineering.

Below are links to all the requests I could find for discrete mathematics:

https://support.khanacademy.org/hc/en-us/community/posts/7112272992525-Discrete-Mathematics-and-Optimization-also-Kalman-Filters
https://support.khanacademy.org/hc/en-us/community/posts/4933699345549-Discrete-Mathematics
https://support.khanacademy.org/hc/en-us/community/posts/4426483762445-Please-add-Discrete-Maths-Courses
https://support.khanacademy.org/hc/en-us/community/posts/4404140714253-Discrete-mathematics
https://support.khanacademy.org/hc/en-us/community/posts/360072384552-Basic-and-advanced-Discrete-Mathematics-
https://support.khanacademy.org/hc/en-us/community/posts/360055112332-Add-Discrete-Mathematics
https://support.khanacademy.org/hc/en-us/community/posts/360043157451--CALL-for-DISCRETE-MATH-COURSES-
https://support.khanacademy.org/hc/en-us/community/posts/360003642811-Request-for-discrete-mathematics-
https://support.khanacademy.org/hc/en-us/community/posts/115006238867-GATE-Exam-CS-IT-
https://support.khanacademy.org/hc/en-us/community/posts/115001400652-I-think-It-would-be-if-we-had-new-subjects-like-advanced
https://support.khanacademy.org/hc/en-us/community/posts/115001094752-Recommending-a-Discrete-Math-teacher-to-Khan-Academy
https://support.khanacademy.org/hc/en-us/community/posts/115000995512-I-would-like-to-see-boolean-algebra-covered-on-khan-academy
https://support.khanacademy.org/hc/en-us/community/posts/115000710291-Discrete-Math
https://support.khanacademy.org/hc/en-us/community/posts/115000394711-Add-higher-level-content
https://support.khanacademy.org/hc/en-us/community/posts/245344727-Upper-division-math
https://support.khanacademy.org/hc/en-us/community/posts/201543634-The-Addition-of-Logic-and-Discrete-Mathematics
https://support.khanacademy.org/hc/en-us/community/posts/201470924-Discrete-Mathematics