Johannes Seppi wrote:
On 27 Oct 2006 17:00:51 GMT, (Dr A. N. Walker)
wrote:

In article _Bq0h.22$gf5.1@trndny01, Chess One wrote:
[...] - it is extraordinary to me that 100k
sequenced datum, which are non-musical could be undertaken - I must suppose
that he calculated the next in sequence [rather than any feat of memory] and
wonder how long it took him to do this overall as well as the typical
interval from one digit to the next?

No, not a chance. There are humanly-computable ways of finding
specific digits in a hexadecimal expansion [and so in binary or octal]
of pi, so you could plausibly ask a skilled mathematician to tell you [eg]
the 1234567th such digit; but no known way of doing it in decimal. If
there were, I'd guess it would take hours, even with a calculator, to
get each digit. Calculating pi to even a few hundred places of decimals
without computer assistance is years of work.

There is no easy way of computing the n-th place of pi in any base, be
it binary, hexadecimal or decimal. There is also no repeating pattern
in this number, regardless od base.

Amazingly there is a specific expansion for Pi in base hexadecimal
found by Simon Plouffe in 1995 see for example:

http://mathworld.wolfram.com/BBPFormula.html

"Easy calculation" here is a relative term, but it is a pretty
astonishing result.

We can safely assume that Akira Haraguchi simply has a somewhat
unusual memory.

Yes, that we can.

Have any of the very deep Pi memorisers explained how they do it?
(I know of various poems for modest lengths but 100k digits is
astonishing)

The only other time I have seen it discussed the person had
synaesthesia and saw number patterns as colours. He could also do some
pretty amazing mental airthmetic too.

Regards,
Martin Brown