A141640 - OEIS

%I #10 Aug 05 2013 03:22:30

%S 1,9,10,18,27,36,45,54,63,69,72,78,81,87,90,96,100,108,117,126,135,

%T 144,153,159,162,168,171,177,180,186,195,207,216,225,234,243,249,252,

%U 258,261,267,270,276,285,294,306,315,324,333,339,342,348,351,357,360,366

%N Additive nonprimes: odd sum of digits is a nonprime.

%C A141468(n)=n-th nonprime.

%H Vincenzo Librandi, <a href="/A141640/b141640.txt">Table of n, a(n) for n = 1..1000</a>

%e Nonprime (7)=10 is additive nonprime because 1+0=1 (odd) is nonprime (2).

%e Nonprime (12)=18 is additive nonprime because 1+8=9 (odd) is nonprime (6), etc.

%t osdnpQ[n_]:=Module[{s=Total[IntegerDigits[n]]},OddQ[s]&&!PrimeQ[s]]; Select[Range[400],osdnpQ] (* _Harvey P. Dale_, Aug 04 2013 *)

%Y Cf. A046704, A141468.

%K nonn,base

%O 1,2

%A _Juri-Stepan Gerasimov_, Sep 03 2008

%E 45 and 207 inserted and extended by _R. J. Mathar_, Sep 05 2008