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It is a well-known fact that John H. E. Cohn proved around 1963 that $144$ is the largest perfect square in the Fibonacci sequence.

Do you happen to know what it is that the initials H and E stand for in the name of this singular mathematician?

From one of those short videos by Eduardo Sáenz de Cabezón I infer that it is not me the only individual that has tried to find out about those initials to no avail.

Please, let me thank you in advance for your answers or comments!

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  • $\begingroup$ You are right: the question 'bout the largest perfect square in the Fibonacci seq. appeared as problem 5080 in the Feb. 1963 issue of the Amer. Math. Monthly: it was posed by A. P. Rollett from Crediton, England. The solution by Oswald Wyler from the University of New Mexico was published on pages 221-222 of the Feb. 1964 issue of the Monthly. Fans of the Monthly know that the editors of the Problem Dept. of the Monthly list the names of all the readers that sent in their solution to a given problem; the lists usually contain several names but in the case of problem 5080, I infer that... $\endgroup$
    – José Hdz. Stgo.
    Commented Jul 29 at 5:12
  • $\begingroup$ ... no other solution was received besides the one submitted by Wyler. All that the editors had to add about the problem on that occasion was the following remark: "The problem is mentioned in Ogilvy, Tomorrow's Math., 1962, p. 100". That being said, I suspected that the issue on the priority regarding the proof of the theorem could arise but I chose to cut to the chase and state my actual question without further ado. $\endgroup$
    – José Hdz. Stgo.
    Commented Jul 29 at 5:15
  • $\begingroup$ Now then, I believe that John H. E. Cohn's proof or the first published version of it actually appeared in the Journal of the London Mathematical Society. As you pointed out earlier today, the proof is to be found on pages 537-540 of the January 1964 of the said journal. I consider that the footnote on page 537 of the article might settle the question on whom the theorem ought to be attributed to; it reads as follows: "Received 20 June, 1963; revised 20 July, 1963". $\endgroup$
    – José Hdz. Stgo.
    Commented Jul 29 at 5:53

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John Hans Edmund Cohn was a Fulbright Scholar and is listed on page 35 of the Directory of Visiting Scholars in the United States Awarded U. S. Government Grants under the Fulbright-Hays Act 1966-1967.

Fulbright directory

From what I can tell, this is the same J. H. E. Cohn who married Anne Ruth Grunfeld in 1961.

Cohn marriage index from GRO

Grunfeld marriage index from GRO

Here is the index for volume 5 c page 1281. Note that there is only one Grunfeld entry, but there are two Cohn entries on the same page, one for Hans E. and one for John H. E., whom I believe to be the same person.

GRO index v 5c p 1281

Their engagement was announced in The Guardian, London, 28 Apr 1961, p. 3:

Cohn-Grunfeld engagement

I have not found any obituaries, and I have found references to both of them within the past 15 years, so it's possible they're both still alive.

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    $\begingroup$ Nice find. This is pure speculation: Hans is the German short for Johannes, which is of course the German long form of John. Perhaps Cohn was a first generation son of German immigrants and he wanted to shift from his given German name to the English version? It might explain the double name entry. $\endgroup$
    – Georg Essl
    Commented Jul 29 at 21:16
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    $\begingroup$ Jewish memorial web site for Attendorn, Germany. Hans Edmund (John) Cohn. Left Germany at age 2 for England, apparently fleeing Nazi Germany. The parenthetical (John) indeed suggest that this part of the name was later adopted. His parents are listed as deceased in England. He is not. Suggests that he may still be alive, if this is current. $\endgroup$
    – Georg Essl
    Commented Jul 29 at 21:22
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    $\begingroup$ Above link is to father Alfred Cohn. Here is the link to Hans Edmund (John). $\endgroup$
    – Georg Essl
    Commented Jul 29 at 21:47
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    $\begingroup$ The December 2023 London Mathematical Society newsletter lists him as among members who would reach more than 60 years of membership during 2024. $\endgroup$
    – Will Orrick
    Commented Jul 29 at 23:48
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    $\begingroup$ Picture of a Nazi mob destroying the Cohn family's store in Attendorn in 1938. $\endgroup$
    – njuffa
    Commented Jul 30 at 3:51

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