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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

Table of n, a(n) for n=1..41.

David Applegate, Marc LeBrun and N. J. A. Sloane, Carryless Arithmetic (I): The Mod 10 Version.

Index entries for 10-automatic sequences.

Index entries for sequences related to carryless arithmetic

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 February 27 11:18 EST 2021. Contains 341649 sequences. (Running on oeis4.)