|
%I #24 Apr 24 2017 10:37:41
%S 20,30,102,120,200,300,1002,1200,2000,2001,2002,3000,3010,10001,10002,
%T 10011,10030,10120,11001,11020,11110,12000,20000,20001,21010,30000,
%U 30030,30100,100001,100030,100101,100130,100210,100300,101001,101101,101200,102102,110001,110200
%N Numbers k such that digit sum of k = number of distinct prime factors of k.
%H Giovanni Resta, <a href="/A285494/b285494.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Range[2,10000],Total[IntegerDigits[#]]==Length[FactorInteger[#]]&] (* or *)
%t nd = 10; s = 1; Sort@ Flatten@ Reap[ While[ Times @@ Prime[ Range@ s] < 10^nd, pa = IntegerPartitions[s, {nd}, Range[0, 9]]; Do[Sow@ Select[ FromDigits /@ Permutations[p], PrimeNu[#] == s &], {p, pa}]; s++]][[2, 1]] (* terms < 10^10, _Giovanni Resta_, Apr 21 2017 *)
%o (PARI) isok(n) = sumdigits(n) == omega(n); \\ _Michel Marcus_, Apr 20 2017
%Y Cf. A001221, A007953, A057531, A057532, A050689, A070274, A070275, A063737, A067077.
%K nonn,base
%O 1,1
%A _Jonathan Frech_, Apr 19 2017
%E More terms from _Michel Marcus_, Apr 20 2017
|
