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Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 10 all are equal.
10

%I #9 Sep 26 2016 19:58:30

%S 1,21,222,223,1230,1231,1502,2200,2201,3012,3013,10431,12214,12215,

%T 12250,12251,14102,15003,15021,16011,20040,20041,22130,23211,23230,

%U 23231,24003,30070,30071,30105,30231,30321,31005,31150,31151,31420

%N Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 10 all are equal.

%H G. C. Greubel, <a href="/A135120/b135120.txt">Table of n, a(n) for n = 1..1100</a>

%e a(2)=21, since ds_2(21)=ds_3(21)=ds_10(21)=3.

%t Select[Range[5000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 3]] == Total[IntegerDigits[#, 10]] &] (* _G. C. Greubel_, Sep 26 2016 *)

%o (PARI) is(n)=my(t=sumdigits(n)); t==hammingweight(n) && t==sumdigits(n,3) \\ _Charles R Greathouse IV_, Sep 26 2016

%Y Cf. A000040, A007953, A054899, A131451, A133620, A133900, A134599, A135110.

%K nonn,base

%O 1,2

%A _Hieronymus Fischer_, Dec 24 2007