Deletion of Mathematical constant Psi

Comment: No published source,  dated in the article from April 2018. Even if the content would deserve a publication (which is not the case), it should be removed per rystal
Stance: delete
Cited policy: Wikipedia:No original research (WP:OR||WP:C)

Comment: per above; clearly  and a duplicate of Sophomore's dream
Stance: delete
Cited policy: Wikipedia:No original research (WP:OR)