Interesting, there seems to be a different Sacks (software engineer Robert Sacks) who devised his own Ulam-like spiral.

Anyway sorry I didn't keep track of the pages I visited, but here are some of the search results I see now, indicating at least some time wasted exploring something that did not need to be explored if it had been clear that the story was not fully real:

BTW the same account of the twins (https://archive.is/MmogP) also has several paragraphs revealing major misunderstandings on the part of Sacks, e.g.:

> And yet they are called “calendar calculators”—and it has been inferred and accepted, on next to no grounds, that what is involved is not memory at all, but the use of an unconscious algorithm for calendar calculations. When one recollects how even Carl Friedrich Gauss, at once one of the greatest of mathematicians, and of calculators too, had the utmost difficulty in working out an algorithm for the date of Easter, it is scarcely credible that these twins, incapable of even the simplest arithmetical methods, could have inferred, worked out, and be using, such an algorithm.

[Needless to say, calculating the day of the week for a fixed date is a much easier and completely unrelated problem to that of Easter, “the first Sunday after the Paschal full moon (a mathematical approximation of the first astronomical full moon, on or after 21 March” https://en.wikipedia.org/wiki/Date_of_Easter ]

Oliver Sacks put himself into his case studies – what was the cost?