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A240265 Numbers n that divide the concatenation of their aliquot divisors, in ascending order. 5
1, 4, 15, 16, 255, 375, 495, 795, 1469, 3825, 9375, 28125, 66375, 67875, 234375, 249487, 286875, 309375, 337185, 450615, 590625, 628125, 1369125, 2390625, 2773125, 2781387, 3069375, 3706785, 4965309, 5859375, 12890625, 13539375, 26803125, 39607575, 62578125 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The sequence is infinite, because it contains all the numbers of the form 3*5^(2k+1). - Giovanni Resta, Apr 03 2014

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

Aliquot divisors of 1469 are 1, 13, 113. Their concatenation in ascending order is 113113 and 113113 / 1469 = 77.

MAPLE

with(numtheory);

T:=proc(t) local x, y; x:=t; y:=0; while x>0 do x:=trunc(x/10); y:=y+1; od; end:

P:=proc(q) local a, b, c, d, i, k, n;

for n from 2 to q do a:=sort([op(divisors(n))]); b:=a[nops(a)-1];

for i from nops(a)-2 by -1 to 1 do b:=b+a[i]*10^T(b); od;

if type(b/n, integer) then print(n); fi;

od; end: P(10^6);

MATHEMATICA

Select[Range[6258*10^4], Divisible[FromDigits[Flatten[IntegerDigits/@ Most[ Divisors[ #]]]], #]&] (* Harvey P. Dale, Aug 21 2019 *)

CROSSREFS

Cf. A069872, A224930.

Sequence in context: A228590 A103540 A065159 * A051956 A308983 A032826

Adjacent sequences:  A240262 A240263 A240264 * A240266 A240267 A240268

KEYWORD

nonn,base

AUTHOR

Paolo P. Lava, Apr 03 2014

EXTENSIONS

a(14)-a(34) from Giovanni Resta, Apr 03 2014

First term (a(1) = 1) prepended by Harvey P. Dale, Aug 21 2019

STATUS

approved

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Last modified January 26 17:16 EST 2020. Contains 331280 sequences. (Running on oeis4.)