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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A124666 Numbers ending in 1, 3, 7 or 9 such that either prepending or following them by one digit doesn't produce a prime. 0
891, 921, 1029, 1037, 1653, 1763, 1857, 2427, 2513, 2519, 2607, 3111, 3193, 3213, 3501, 3519, 3707, 3953, 4227, 4459, 4599, 4689, 4803, 4863, 5019, 5043, 5047, 5397, 5459, 5489, 5499, 6019, 6023, 6429, 6483, 6609, 6621, 7113 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If the number doesn't end in 1, 3, 7 or 9, then the prepending requirement is automatically satisfied. Hence it becomes nonrestrictive and not very interesting.

LINKS

Table of n, a(n) for n=1..38.

EXAMPLE

The definition means that 891, 1891, 2891, 3891, 4891, 5891, 6891, 7891, 8891, 9891, 8911, 8913, 8917 and 8919 are all composite numbers.

CROSSREFS

Sequence in context: A110726 A204366 A266915 * A125303 A087672 A284842

Adjacent sequences:  A124663 A124664 A124665 * A124667 A124668 A124669

KEYWORD

base,nonn

AUTHOR

Tanya Khovanova, Dec 23 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 May 23 02:46 EDT 2017. Contains 286909 sequences.