A simple proof that pi is irrational by Ivan Niven
= A simple proof that pi is irrational by Ivan Niven
{c}
{tag=Work by Ivan Niven}
{title2=1947}
Bulletin of the American Mathematical Society 53(6), page 509. DOI: https://doi.org/10.1090/S0002-9904-1947-08821-2
One-page original article scan: https://nonagon.org/ExLibris/sites/default/files/pdf/Niven-Pi-Irrational.pdf
The factorial-normalized polynomial, its integer endpoint derivatives and the positive integral tending to zero provide the complete elementary proof.