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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A075824 Odd numbers that cannot be expressed as 2^n-3^m where n and m are integers. 2
9, 11, 17, 19, 21, 25, 27, 33, 35, 39, 41, 43, 45, 49, 51, 53, 57, 59, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 103, 105, 107, 109, 111, 113, 115, 117, 121, 123, 129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 157 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All listed terms can be certified by considering 2^n-3^m modulo 2552550. [Max Alekseyev, Feb 08 2010]

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, D9.

T. N. Shorey and R. Tijdeman, Exponential Diophantine Equations, Cambridge University Press, 1986.

LINKS

Table of n, a(n) for n=1..61.

T. Metsankyla, Catalan's Conjecture : Another old Diophantine problem solved, Bull. Amer. Math. Soc. 41 (2004), 43-57.

Wikipedia, Catalan's conjecture

EXAMPLE

5 doesn't belong to the sequence because it can be expressed as 2^3-3^1.

CROSSREFS

Complement of A192110 in the odd integers.

Cf. A074981.

Sequence in context: A216976 A236390 A048464 * A228951 A108113 A111391

Adjacent sequences:  A075821 A075822 A075823 * A075825 A075826 A075827

KEYWORD

nonn

AUTHOR

Felice Russo, Oct 14 2002

EXTENSIONS

Inserted "odd" in definition. - N. J. A. Sloane, Jan 30 2009

Jon E. Schoenfield observed that 49 was missing, Jan 30 2009

More terms from Max Alekseyev, Feb 08 2010

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 17:04 EDT 2019. Contains 327311 sequences. (Running on oeis4.)