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A135122
Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 4 all are equal.
3
1, 21, 261, 273, 17748, 17749, 20820, 20821, 65620, 65621, 70740, 70741, 83268, 83269, 86292, 86293, 1066068, 1066069, 1070420, 1135701, 1135893, 1135953, 5326161, 5330001, 5330241, 5330260, 5330261, 5506389, 5525829, 5526801, 5571909, 5574933, 5592321
OFFSET
1,2
LINKS
EXAMPLE
a(2)=21, since ds_2(21)=ds_3(21)=ds_10(21)=3, where ds_x=digital sum base x.
MATHEMATICA
Select[Range[5600000], Length[Union[Table[Total[IntegerDigits[#, n]], {n, 2, 4}]]]==1&] (* Harvey P. Dale, Aug 14 2013 *)
PROG
(PARI) isok(n) = my(sd2=sumdigits(n, 2)); (sd2==sumdigits(n, 3)) && (sd2==sumdigits(n, 4)); \\ Michel Marcus, Aug 08 2018
KEYWORD
nonn,base
AUTHOR
Hieronymus Fischer, Dec 31 2007
EXTENSIONS
a(31)-a(33) from Giovanni Resta, Aug 06 2018
STATUS
approved