Sliding numbers
Eric Angelini
keynews.tv at skynet.be
Wed Mar 9 13:22:30 CET 2005
Hello SeqFan and Math-fun,
Let's start with an example of "sliding number":
1/4 + 1/25 = 0.29 --> 29 is a "sliding number"
1/8 + 1/125 = 0.133 --> 133 is a "sliding number"
1/2 + 1/5 = 0.7 --> 7 is a "sliding number"
etc.
Note that :
1/20 + 1/50 = 0.70 --> 70 is a "sliding number"
though 0.70 is usually written 0.7
So any "sliding number" G produces an infinite
quantity of others : Gx10, Gx100, Gx1000, etc.
Generally speaking we have this:
1/a + 1/b = (a+b)/10^k [with k=1,=2,=3,=4, ...]
--> the "sliding number" G = a+b
My pb is to build a correct seq. of G's (how not
to forget any G behind?)
By hand I've proceeded so:
10 --> 1+10 --> G(2)=11
2+5 --> G(1)=7
100 --> 1+100 --> G(7)=101
2+50 --> G(6)=52
4+25 --> G(5)=29
5+20 --> G(4)=25
10+10 --> G(3)=20
1000 --> 1+1000 --> G(15)=1001
2+500 --> G(14)502
4+250 --> G(13)=254
5+200 --> G(12)=205
8+125 --> G(11)133
10+100 --> G(10)=110
20+50 --> G(9)=70
25+40 --> G(8)=65
... but you see now my pb: G(8) and G(9) are < G(7) !
I have to rename them...
The sequence would then start like this:
7,11,20,25,29,52,65,70,101,110,133,205...
BUT:
10000 --> 100+100 (among others) which gives G=200...
So I have to correct the sequence and insert 200:
7,11,20,25,29,52,65,70,101,110,133,200,205...
[BTW 200 is G(3)x10]
Could someone compute enough terms to be submitted
to the OEIS without leaving any G integer behind?
Many thanks,
É.
-----------
PS. I don't know who has given the name "sliding
numbers" to those integers -- I might have read
that on the Internet somewhere around 1997...
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