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!)
A141640 Additive nonprimes: odd sum of digits is a nonprime. 1
1, 9, 10, 18, 27, 36, 45, 54, 63, 69, 72, 78, 81, 87, 90, 96, 100, 108, 117, 126, 135, 144, 153, 159, 162, 168, 171, 177, 180, 186, 195, 207, 216, 225, 234, 243, 249, 252, 258, 261, 267, 270, 276, 285, 294, 306, 315, 324, 333, 339, 342, 348, 351, 357, 360, 366 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
A141468(n)=n-th nonprime.
LINKS
EXAMPLE
Nonprime (7)=10 is additive nonprime because 1+0=1 (odd) is nonprime (2).
Nonprime (12)=18 is additive nonprime because 1+8=9 (odd) is nonprime (6), etc.
MATHEMATICA
osdnpQ[n_]:=Module[{s=Total[IntegerDigits[n]]}, OddQ[s]&&!PrimeQ[s]]; Select[Range[400], osdnpQ] (* Harvey P. Dale, Aug 04 2013 *)
CROSSREFS
Sequence in context: A058369 A110939 A260042 * A231504 A298979 A299969
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
45 and 207 inserted and extended by R. J. Mathar, Sep 05 2008
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 March 29 01:36 EDT 2024. Contains 371264 sequences. (Running on oeis4.)