The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A196509 Largest palindrome formed by using n single-digit numbers and the operators +, -, * and / where concatenation is not allowed. 0
9, 11, 343, 747, 6556, 65856, 405504, 4251524, 8847488 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
This puzzle is easily trivial if exponentiation or concatenation is allowed.
Best known results for a(10)..a(15) are 88499488, 846747648, 4095995904, 23613431632, 68899199886, 633498894336.
Erich Friedman solved and proved most of these terms.
LINKS
EXAMPLE
11 = 9 + 2
343 = 7 * 7 * 7
747 = 9 * (9 * 9 + 2)
6556 = 9 * 9 * 9 * 9 - 5
65856 = 3 * 7 * 7 * 8 * 8 * 8
405504 = 8 * 8 * 8 * 8 * 9 * (9 + 2)
4251524 = 8 * 9 * 9 * 9 * 9 * 9 * 9 - 4
8847488 = 8 * 8 * (5 * 6 * 8 * 8 * 8 * 9 + 2)
CROSSREFS
Cf. A002113.
Sequence in context: A146603 A159003 A352004 * A269026 A124606 A110647
KEYWORD
nonn,base,more
AUTHOR
Kausthub Gudipati, Oct 03 2011
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 13 17:32 EDT 2024. Contains 373391 sequences. (Running on oeis4.)