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A287442 Numbers k = concat( x, y ), not ending in 0, such that  x * y divides k. 1
11, 12, 15, 24, 36, 101, 102, 104, 105, 125, 208, 306, 315, 735, 1001, 1002, 1004, 1005, 1008, 1025, 1125, 1352, 1734, 2016, 3006, 3015, 3024, 3375, 6048, 7007, 7056, 9072, 10001, 10002, 10004, 10005, 10008, 10016, 10025, 10125, 10625, 11011, 13013, 14112, 18144 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers ending in zero are not listed because of the form a(n) * 10^k, with k>0.

LINKS

Table of n, a(n) for n=1..45.

Paolo P. Lava, First 250 terms with their ratios

EXAMPLE

36 = concat(3,6) and 36 / (3*6) = 2;

3375 = concat(3,375) and 3375 / (3*375) = 3;

18144 = concat(18,144) and 18144 / (18*144) = 7.

MAPLE

P:=proc(q) local a, k, n; for n from 1 to q do if not n mod 10=0 then

for k from 1 to ilog10(n) do a:=n/((n mod 10^k)*trunc(n/10^k));

if type(a, integer) then print(n); break; fi; od; fi; od; end: P(10^9);

MATHEMATICA

cxyQ[n_]:=Module[{idn=IntegerDigits[n]}, idn[[-1]]!=0&&AnyTrue[ Table[ FromDigits/@TakeDrop[idn, k], {k, Length[idn]-1}], Divisible[n, Times@@#]&]]; Select[Range[20000], cxyQ] (* The program uses the AnyTrue function from Mathematica version 10 *)(* Harvey P. Dale, Mar 09 2018 *)

CROSSREFS

Sequence in context: A249766 A113600 A255725 * A255726 A097158 A072239

Adjacent sequences:  A287439 A287440 A287441 * A287443 A287444 A287445

KEYWORD

nonn,base,easy

AUTHOR

Paolo P. Lava, May 25 2017

STATUS

approved

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Last modified June 25 09:48 EDT 2019. Contains 324347 sequences. (Running on oeis4.)