Impressive. But, as often with J, not immediately comprehensible. - Bo --- Den lør 22/8/09 skrev Roger Hui <[email protected]>:
> Fra: Roger Hui <[email protected]> > Emne: Re: [Jprogramming] Unforgettable times > Til: "Programming forum" <[email protected]> > Dato: lørdag 22. august 2009 23.41 > j #~ (j e. <:p: j) * (j e. > >:*:j) * (2...@q: j) * 2...@q:@(|.&.":"0) j=: 1+i.1e6 > 226 47962 95482 103042 140626 194482 370882 > > > > ----- Original Message ----- > From: Roger Hui <[email protected]> > Date: Saturday, August 22, 2009 14:29 > Subject: Re: [Jprogramming] Unforgettable times > To: Programming forum <[email protected]> > > > 226: the first emirprime which is the successor of > > a perfect square and the precedessor of a prime. > > > > http://mathworld.wolfram.com/Emirpimes.html > > > > > > > > ----- Original Message ----- > > From: Randy MacDonald <[email protected]> > > Date: Saturday, August 22, 2009 13:42 > > Subject: Re: [Jprogramming] Unforgettable times > > To: Programming forum <[email protected]> > > > > > What is memorable about 226? > > > > > > Roger Hui wrote: > > > > The problem is that _every_ number has > something > > > > notable about it, so that each number is > "unforgettable" > > > > and consequently it's hard to remember any > single > > > > one of them. > > > > > > > > 0000 all zeros > > > > 0001 first counting number > > > > 0002 first prime number > > > > 0003 first odd prime > > > > 0004 first composite number > > > > ... > > > > 24 60 #: ?. */ 24 60 > > > > 1 6 > > > > > > > > 0106 first number greater than 100 with 2 > prime factors > > > > > > > > etc. > > > > > > > > You have most likely heard of the story > about Hardy > > > > and Ramanujan. One day Hardy took a taxi > to visit > > > > Ramanujan. On arriving Hardy told > Ramanujan that > > > > the taxi had the 4-digit number n on its > license plate, > > > > a thoroughly unremarkable number. > Ramanujan > > > > immediately remarked that n is the first > number that ... . > > > > I forget what n or the property was, > something like, > > > > n is the first number that can be written as > the sum > > > > of two perfect cubes in two different ways, > something > > > > typically Ramanujanish. > > > > > > > > Yes, that was it: > > > > > > > > c=: i*i*i=: >:i.200 > > > > t=: (</~i.200) * +/~c > > > > d=: </.~ ,t > > > > (2=#&>d)#d > > > > > +---------+---------------+---------------+---------+-- > > > > |1729 1729|1092728 1092728|3375001 > 3375001|4104 4104| ... > > > > > +---------+---------------+---------------+---------+-- > > > > <./ {.&> (2=#&>d)#d > > > > 1729 > > > > I. , 1729 = t > > > > 11 1609 > > > > 1 + (#t) #: 11 1609 > > > > 1 12 > > > > 9 10 > > > > +/ 1 12 ^ 3 > > > > 1729 > > > > +/ 9 10 ^ 3 > > > > 1729 > > > > > > > > Now that I have worked out the number I can > find the > > > > story on the net: http://en.wikipedia.org/wiki/1729_(number) > > > > > > > > p.s. In my youth, when I needed to remember > a (5-digit) > > > > number for a time, I would try to compute > its largest > > > > prime factor by mental calculation. Try it > and you'll > > > > see why that works. > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > From: Kip Murray <[email protected]> > > > > Date: Saturday, August 22, 2009 5:27 > > > > Subject: Re: [Jprogramming] Unforgettable > times > > > > To: Programming forum <[email protected]> > > > > > > > > > > > >> To narrow the puzzle, > > > >> > > > >> times 3 4 5 NB. Unforgettable > > > >> 1 6 2 0 > > > >> 1 8 1 2 > > > >> 1 2 0 7 > > > >> timedata i. 1 8 1 2 > > > >> 4 > > > >> times i.8 > > > >> 1 2 3 4 > > > >> 1 4 1 4 > > > >> 1 4 2 8 > > > >> 1 6 2 0 > > > >> 1 8 1 2 > > > >> 1 2 0 7 > > > >> 1 2 3 4 > > > >> 1 4 1 4 > > > >> > > > >> You are encouraged to choose your own > unforgettable times > > > seen > > > >> on a 24-hour > > > >> digital clock. > > > >> > > > >> > > > >> Kip Murray wrote: > > > >> > > > >>> Who could forget > > > >>> > > > >>> times 3 4 5 > > > >>> 1 6 2 0 > > > >>> 1 8 1 2 > > > >>> 1 2 0 7 > > > >>> > > > >>> ? > > > >>> > > > >>> Kip Murray wrote: > > > >>> > > > >>>> Write a verb that produces > unforgettable times on a 24- > > hour > > > >>>> > > > >> digital clock: who > > > >> > > > >>>> could forget an appointment at > 12:34 or 14:14 or 14:28 > > > >>>> > > > >> ? It's too bad that > > > >> > > > >>>> 31:41 , 27:18 and 69:31 do not > fit on the clock. > > > >>>> > > > >>>> times 0 > > > >>>> 1 2 3 4 > > > >>>> times 0 1 > > > >>>> 1 2 3 4 > > > >>>> 1 4 1 4 > > > >>>> times i. 5 > > > >>>> 1 2 3 4 > > > >>>> 1 4 1 4 > > > >>>> 1 4 2 8 > > > >>>> 1 2 3 4 > > > >>>> 1 4 1 4 > > > >>>> NB. Oh, well, you > will > > > do > > > >>>> > > > >> better than this > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > Trænger du til at se det store billede? Kelkoo giver dig gode tilbud på LCD TV! Se her http://dk.yahoo.com/r/pat/lcd ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
