login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A125520 a(n) = maximal difference between two distinct n-digit with property that when one of them is typed into a calculator and rotated 180 degrees, the other one is seen. 0
3, 75, 825, 8835, 89235, 898335, 8992335, 89983335, 899923335, 8999833335, 89999233335, 899998333335, 8999992333335 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..13.

FORMULA

If n is greater than 2 and even, than a(n) is 8 followed by (n / 2) - 2 nines followed by another 8 followed by (n / 2) - 1 threes followed by 5. If n is greater than 2 and odd, than a(n) is 8 followed by (n / 2) - 1.5 nines followed by a 2 followed by (n / 2) - 1.5 threes followed by a 5.

EXAMPLE

a(2) = 75. If someone types 91 into a calculator and rotates it 180 degrees, they will get 16. 91 - 16 = 75. It is easy to check that no larger differences can be obtained.

CROSSREFS

Sequence in context: A265956 A189805 A230145 * A163131 A060869 A012491

Adjacent sequences:  A125517 A125518 A125519 * A125521 A125522 A125523

KEYWORD

base,nonn

AUTHOR

Tanya Khovanova and Sergei Bernstein, Dec 29 2006

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 24 02:32 EDT 2017. Contains 291052 sequences.