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 A168541 Numbers consisting of either 2's and 0's or 5's and 0's. 5
 2, 5, 20, 50, 200, 202, 220, 500, 505, 550, 2000, 2002, 2020, 2022, 2200, 2202, 2220, 5000, 5005, 5050, 5055, 5500, 5505, 5550, 20000, 20002, 20020, 20022, 20200, 20202, 20220, 20222, 22000, 22002, 22020, 22022, 22200, 22202, 22220, 50000, 50005 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A subset of the divisors of zero in carryless arithmetic mod 10, e.g., 5 * 44 = 0. LINKS David Applegate, Marc LeBrun and N. J. A. Sloane, Carryless Arithmetic (I): The Mod 10 Version. MATHEMATICA lst = {2, 5}; k = 1; While[k < 10^5, id = Union@ IntegerDigits@k; len = Length@ id; If[ len == 2 && id == {0, 2} || id == {0, 5}, AppendTo[lst, k]]; k++ ]; lst (* Robert G. Wilson v, Jul 12 2010 *) Join[{2, 5}, Sort[Flatten[Table[Select[FromDigits/@Tuples[{k, 0}, 6], DigitCount[ #, 10, 0]>0 && DigitCount[#, 10, k]>0&], {k, {2, 5}}]]]] (* Harvey P. Dale, Jul 03 2020 *) CROSSREFS Cf. A004520, A059729, A168294, A169884. Sequence in context: A136901 A136897 A098510 * A124264 A274239 A271858 Adjacent sequences: A168538 A168539 A168540 * A168542 A168543 A168544 KEYWORD nonn,base,easy AUTHOR David Applegate, Marc LeBrun and N. J. A. Sloane, Jul 06 2010 EXTENSIONS More terms from Robert G. Wilson v, Jul 12 2010 STATUS approved

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Last modified March 27 13:28 EDT 2023. Contains 361572 sequences. (Running on oeis4.)