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Composite numbers n such that digit sum of n equals digit sum of sum of its prime factors (counted with multiplicity).
4

%I #14 Nov 30 2020 22:36:19

%S 4,22,27,94,105,114,121,150,166,202,204,222,224,265,274,315,342,346,

%T 355,382,438,445,450,454,517,526,540,562,612,634,640,706,841,852,913,

%U 915,922,1068,1086,1111,1120,1122,1138,1165,1185,1200,1219,1221,1230

%N Composite numbers n such that digit sum of n equals digit sum of sum of its prime factors (counted with multiplicity).

%t ds[n_]:=Total[IntegerDigits[n]]; t={}; Do[If[!PrimeQ[n]&&ds[n]==ds[Total[ Times@@@FactorInteger[n]]],AppendTo[t,n]],{n,4,1230}]; t (* _Jayanta Basu_, Jun 04 2013 *)

%Y Cf. A006753, A036921, A019506.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jan 04 1999

%E Title made more precise by _Sean A. Irvine_, Nov 30 2020