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A129845
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Numbers n such that n and 2n share at least one digit.
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8
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10, 12, 20, 21, 24, 25, 26, 30, 37, 40, 42, 47, 49, 50, 51, 60, 61, 62, 63, 68, 70, 71, 74, 75, 80, 81, 84, 87, 89, 90, 91, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 112, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 132, 137
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graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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The smallest term sharing more than one digit with its double is 102. - Alonso del Arte, Apr 16 2014
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LINKS
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EXAMPLE
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10 is in the sequence because 2 * 10 = 20, which has a 0 in common with 10.
12 is in the sequence because 2 * 12 = 24, which has a 2 in common with 12.
14 is not in the sequence because 2 * 14 = 28, which has no digits in common with 14.
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MAPLE
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a:=proc(n) if nops(convert(convert(n, base, 10), set) intersect convert(convert(2*n, base, 10), set))>0 then n else fi end: seq(a(n), n=1..170); # Emeric Deutsch, May 27 2007
isA129845 := proc(n) local twon, digsn, digs2n, i ; twon := 2*n ; digsn := convert(n, base, 10) ; digs2n := convert(twon, base, 10) ; for i from 1 to nops(digsn) do if op(i, digsn) in digs2n then RETURN(true) ; fi ; od ; RETURN(false) ; end: for n from 1 to 200 do if isA129845(n) then printf("%d, ", n) ; fi ; od ; # R. J. Mathar, Jun 08 2007
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MATHEMATICA
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Select[Range[300], Length[Intersection[IntegerDigits[#], IntegerDigits[2#]]] > 0 &] (* Stefan Steinerberger, May 24 2007 *)
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PROG
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(Haskell)
a129845 n = a129845_list !! (n-1)
a129845_list =
filter (\x -> not $ null (show (2*x) `intersect` show x)) [1..]
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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