In the sitcom M*A*S*H, why was the number 4077 selected as the 4077th Mobile Army Surgical Hospital?

M*A*S*H is an acronym for Mobile Army Surgical Hospital.

The subsequent film and television series were based on the works of Richard Hooker (H. Richard Hornberger), himself a surgeon at M*A*S*H 8055 in Korea.

There was no M*A*S*H 4077, the unit number is fictitious. M*A*S*H units were part of the U.S. 8th Army and their unit numbers began with "8". People have speculated as to the significance of "4077", but there does not seem to be any definitive answer.

https://wiki2.org/en/M*A*S*H+Newton

Here is another explanation, however the explanation "doesn't add up"...

In 1968, surgeon H. Richard Hornberger-using the nom de plume of Richard Hooker-collaborated with writer W.C. Heinz to create the book MASH: A Novel About Three Army Doctors, based on his experiences with the 8055th Mobile Army Surgical Hospital during the Korean War. Two years later, Robert Altman used the book as the basis for a movie about the fictional 4077th unit (he cut the number 8055 in half).

https://www.mentalfloss.com/article/68457/17-painless-facts-about-mash