A159251 - OEIS

%I #4 Mar 30 2012 17:28:00

%S 12,14,16,20,21,25,30,32,34,50,52,70,102,104,106,110,111,115,120,122,

%T 124,133,140,142,160,200,201,203,205,210,212,214,221,230,232,250,300,

%U 302,304,320,322,340,403,410,412,430,500,502,511,520,610,700,1001,1002

%N Composite numbers whose digit sum is a single-digit prime.

%C Numbers of (2..6)-digit terms are 12,40,105,260,543. [From _Zak Seidov_, Apr 12 2009]

%e 250 is a composite number whose digit sum of 7 is a single-digit prime.

%t s={};Do[t=Total[IntegerDigits[n]];If[ !PrimeQ[n]&&(t-2)(t-3)(t-5)(t-7)== 0,AppendTo[s,n]],{n,7*10^3}];s [From _Zak Seidov_, Apr 12 2009]

%Y Cf. A002808 (composite numbers), A157496.

%K nonn,base,easy,less

%O 1,1

%A _Parthasarathy Nambi_, Apr 06 2009

%E Extended, minor edits and keywords easy, less added by _Klaus Brockhaus_, Apr 12 2009

%E More terms from _Zak Seidov_, Apr 12 2009