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Least positive multiple of n that when written in base 10 has digits in nonincreasing order.
2

%I #12 Mar 26 2013 14:07:22

%S 1,2,3,4,5,6,7,8,9,10,11,60,52,42,30,32,51,54,76,20,21,22,92,72,50,52,

%T 54,84,87,30,31,32,33,442,70,72,74,76,663,40,41,42,43,44,90,92,94,96,

%U 98,50,51,52,53,54,55,840,741,522,531,60,61,62,63,64,65,66,871,544,552,70,71,72,73,74,75,76,77,6552,553,80,81,82,83,84,85

%N Least positive multiple of n that when written in base 10 has digits in nonincreasing order.

%C This sequence is well defined (same reasoning as for A079339).

%H Giovanni Resta, <a href="/A223474/b223474.txt">Table of n, a(n) for n = 1..2000</a>

%e a(39) = 663 because it is the least multiple of 39 appearing in A009996.

%t a[n_] := Block[{x=n}, While[0 < Max@Differences@IntegerDigits@x, x += n]; x]; Array[a, 85] (* _Giovanni Resta_, Mar 26 2013 *)

%o (Perl)

%o sub A223474 {

%o my $n = shift;

%o my $a = $n;

%o while ($a !~ /^9*8*7*6*5*4*3*2*1*0*$/) {

%o $a += $n;

%o }

%o return $a;

%o }

%o foreach (1..100) {

%o print A223474($_), ",";

%o }

%Y a(n)/n yields sequence A223475.

%Y Cf. A004290, A181060.

%Y Cf. A009996.

%K nonn,base

%O 1,2

%A _Paul Tek_, Mar 20 2013