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 A080718 1, together with numbers n that are the product of two primes p and q such that the multiset of the digits of n coincides with the multiset of the digits of p and q. 7
 1, 1255, 12955, 17482, 25105, 100255, 101299, 105295, 107329, 117067, 124483, 127417, 129595, 132565, 145273, 146137, 149782, 174082, 174298, 174793, 174982, 250105, 256315, 263155, 295105, 297463, 307183, 325615, 371893, 536539 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Except for 1, this sequence is a subsequence of A280928. More specifically, members of A280928 are also members of this sequence if and only if they are semiprime. - Ely Golden, Jan 11 2017 This sequence has no equivalent in odd bases. This is because any equivalent of A280928 in an odd base must have all terms having at least 3 prime factors. - Ely Golden, Jan 11 2017 All entries other than 1 are congruent to 4 mod 9, because p*q == p + q mod 9 (with p and q not both divisible by 3) implies p*q == 4 mod 9. - Robert Israel, May 05 2014 LINKS Robert Israel, Table of n, a(n) for n = 1..145 EXAMPLE 1255 = 5*251, 12955 = 5*2591, 17482 = 2*8741, 100255 = 5*20051, 146137=317*461, etc. MAPLE filter:= proc(n) local F, p, q, Ln, Lpq;   F:= ifactors(n);   if nops(F) > 2 or convert(F, `+`)<>2 then return false fi;   p:= F;   if nops(F) = 2 then q:= F else q:= F fi;   Ln:= sort(convert(n, base, 10));   Lpq:= sort([op(convert(p, base, 10)), op(convert(q, base, 10))]);   evalb(Ln = Lpq); end proc: filter(1):= true: A080718:= select(filter, [1, seq(4+9*i, i=1..10^6)]); # Robert Israel, May 04 2014 MATHEMATICA ptpQ[n_]:=Module[{sidn=Sort[IntegerDigits[n]], fi=Transpose[ FactorInteger[ n]]}, fi[]=={1, 1}&&Sort[Flatten[ IntegerDigits/@ fi[]]]==sidn]; Join[{1}, Select[Range[4, 550000, 9], ptpQ]] (* Harvey P. Dale, Jun 22 2014 *) CROSSREFS The following sequences are all closely related: A020342, A014575, A080718, A280928, A048936, A144563. Sequence in context: A067203 A230544 A280928 * A219993 A237562 A304829 Adjacent sequences:  A080715 A080716 A080717 * A080719 A080720 A080721 KEYWORD nonn,base AUTHOR Jeff Heleen, Mar 06 2003 EXTENSIONS Edited by N. J. A. Sloane, Jan 03 2009 Incorrect entry 163797 removed by Robert Israel, May 04 2014 STATUS approved

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Last modified July 6 17:41 EDT 2020. Contains 335479 sequences. (Running on oeis4.)