duplicate hunting, pt. 6

[Andrew Plewe]

> 
> Possible duplicates:
> 
> A055377 and A108563
> 
> 
> 	-Andrew Plewe-
> 
These two are equivalent as well.  Primes > n/2 don't appear as factors of A025507(n) since they appear once in n! and
again in the denominator LCM[1,...,n].  Primes <= n/2 appear more times in the numerator than the denominator so they
appear in the fraction.  So A055377 is largest prime <= [n/2].  It is easy to see that A108563 is also largest prime <=
[n/2] as the comment indicates.  Curious that the offsets are different - I think 4 is correct for both since
A025507(3)=1 has no prime factors.  

Ray Chandler





I'm giving a talk in the Applied Math Dept at MIT on Monday Apr 30 
about the OEIS. Tea at 4:00 in Room 4-174 (Math Majors Lounge),
talk 4.30-5.30 in Room 2-105.  See http://www-math.mit.edu/amc/spring07/
for more information and a link to a nice poster.  I'm hoping this
will be an opportunity to meet OEIS fans that I've never met as well
as to see old friends.
I haven't mentioned this to my hosts yet, but my plan is to replace
the usual post-colloquium dinner by a more informal party - at some local
pub - where the old seq-fans, together with new people who
were at the talk, can get together and have fun!
Note to Richard Stanley: you may be the unique person common
to these mailing lists and the math dept.: hope you approve
of the plan!

Looking forward to seeing you all on Monday!

Neil



Straightforward duplicates:

A120358 and A120363
A111016 and A111017
A063768 and A104085
A117133 and A117155
A090699 and A118889
A108183 and A109405
A102874 and A102876 and A102877
A062680 and A107615
A060566 and A073104


Possible duplicates:

A075643 and A076074


A062679 is apparently missing some terms. The definition is "Numbers such
that every divisor (except 1) contains the digit 9.", however it only lists
primes ending in 9 (making it the same sequence as A106093). I believe the
Sequences A100694 and A100697 could use some editing; the titles are unclear
and the examples don't seem to match the definitions of those sequences.
Because of these discrepancies I'm also suspicious of the correctness of the
terms in both of those sequences.