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A207830
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Positive multiples of 3 that contain the decimal digit 1.
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0
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12, 15, 18, 21, 51, 81, 102, 105, 108, 111, 114, 117, 120, 123, 126, 129, 132, 135, 138, 141, 144, 147, 150, 153, 156, 159, 162, 165, 168, 171, 174, 177, 180, 183, 186, 189, 192, 195, 198, 201, 210, 213, 216, 219, 231, 261, 291, 312, 315, 318, 321, 351, 381, 411, 414
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text;
internal format)
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OFFSET
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1,1
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COMMENTS
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I came across this sequence while working some problems in ALCUMUS from the AoPS site. [Tyler]
A 10-automatic set: members are numbers with decimal expansions matching a regular expression. - Charles R Greathouse IV, Feb 20 2012
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REFERENCES
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MathCounts 2006 National Target #5
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LINKS
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MATHEMATICA
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Select[3*Range[138], DigitCount[#, 10, 1] > 0 &] (* Alonso del Arte, Feb 20 2012 *)
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PROG
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(PARI) is(n)=if(n%3, return(0)); n=vecsort(eval(Vec(Str(n))), , 8); n[1]==1||(#n>1&&n[2]==1) \\ Charles R Greathouse IV, Feb 20 2012
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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