Neo Euler Font

AMS Euler is an upright cursive typeface, commissioned by the American Mathematical Society (AMS) and designed and created by Hermann Zapf with the assistance of Donald Knuth and his Stanford graduate students. It tries to emulate a mathematician's style of handwriting mathematical entities on a blackboard, which is upright rather than italic

Khaled Hosny converted this to an OpenType font.

Source: https://github.com/khaledhosny/euler-otf
Article: http://tug.org/TUGboat/Articles/tb29-2/tb92hagen-euler.pdf
Reference: https://en.wikipedia.org/wiki/AMS_Euler