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Integers n such that the sum of the digits of n is not prime.
8

%I #14 Jul 05 2024 09:32:49

%S 1,4,6,8,9,10,13,15,17,18,19,22,24,26,27,28,31,33,35,36,37,39,40,42,

%T 44,45,46,48,51,53,54,55,57,59,60,62,63,64,66,68,69,71,72,73,75,77,78,

%U 79,80,81,82,84,86,87,88,90,91,93,95,96,97,99,100,103,105,107,108,109,112

%N Integers n such that the sum of the digits of n is not prime.

%H Vincenzo Librandi, <a href="/A104211/b104211.txt">Table of n, a(n) for n = 1..1000</a>

%e Sum of digits of 15=6 not prime.

%t Select[Range[250], !PrimeQ[Total[IntegerDigits[ # ]]]&] (* _Vincenzo Librandi_, Apr 17 2013 *)

%o (PARI) lista(n) = { my(x,y); for(x=1,n, y=sumdigits(x); if(!isprime(y), print1(x,", ") ) ); }

%Y Complement of A028834.

%Y Cf. A000040, A007953.

%K easy,nonn,base

%O 1,2

%A _Cino Hilliard_, Mar 13 2005