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A235691
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Semiprimes which have one or more occurrences of exactly three different digits.
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4
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106, 123, 129, 134, 142, 143, 145, 146, 158, 159, 169, 178, 183, 185, 187, 194, 201, 203, 205, 206, 209, 213, 214, 215, 217, 218, 219, 235, 237, 247, 249, 253, 254, 259, 265, 267, 274, 278, 287, 289, 291, 295, 298, 301, 302, 305, 309, 314, 319, 321, 326, 327
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OFFSET
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1,1
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COMMENTS
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The first term having a repeated digit is 1003.
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LINKS
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EXAMPLE
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91119111691966691969 is a term, because it is made of the 3 digits {1, 6, 9} and is the product of two primes 9397848521 and 9695741689. - Giovanni Resta, Jan 14 2014
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MATHEMATICA
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Select[Range@999, Length@ Union@ IntegerDigits[#] == 3 && Total[Last /@ FactorInteger[#]] == 2 &] (* Giovanni Resta, Jan 14 2014 *)
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PROG
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(PARI)
list(lim)=my(v=List(), t); forprime(p=2, sqrt(lim), t=p; forprime(q=p, lim\t, listput(v, t*q))); vecsort(Vec(v)) \\ From A001358
b=list(10000); s=[]; for(n=1, #b, if(#vecsort(eval(Vec(Str(b[n]))), , 8)==3, s=concat(s, b[n]))); s
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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