

A007602


Numbers that are divisible by the product of their digits.
(Formerly M0482)


49



1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 24, 36, 111, 112, 115, 128, 132, 135, 144, 175, 212, 216, 224, 312, 315, 384, 432, 612, 624, 672, 735, 816, 1111, 1112, 1113, 1115, 1116, 1131, 1176, 1184, 1197, 1212, 1296, 1311, 1332, 1344, 1416, 1575, 1715, 2112, 2144
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OFFSET

1,2


COMMENTS

These are called Zuckerman numbers to base 10. [Sonamed by J. J. Tattersall, after Herbert S. Zuckerman.  Charles R Greathouse IV, Jun 06 2017]  Howard Berman (howard_berman(AT)hotmail.com), Nov 09 2008
This sequence is a subsequence of A180484; the first member of A180484 that is not a member of A007602 is 1114.  D. S. McNeil, Sep 09 2010
Complement of A188643; A188642(a(n)) = 1; A038186 is a subsequence; A168046(a(n)) = 1: subsequence of A052382.  Reinhard Zumkeller, Apr 07 2011
The terms of n digits in the sequence, for n from 1 to 14, are 9, 5, 20, 40, 117, 285, 747, 1951, 5229, 13493, 35009, 91792, 239791, 628412, 1643144, 4314987. Empirically, the counts seem to grow as 0.858*2.62326^n.  Giovanni Resta, Jun 25 2017
De Koninck and Luca showed that the number of Zuckerman numbers below x is at least x^0.122 but at most x^0.863.  Tomohiro Yamada, Nov 17 2017


REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

Reinhard Zumkeller and Zak Seidov, Table of n, a(n) for n = 1..10000
JeanMarie De Koninck and Florian Luca, Positive integers divisible by the product of their nonzero digits, Port. Math. 64 (2007) 7585. (This proof for upper bounds contains an error. See the paper below)
JeanMarie De Koninck and Florian Luca, Corrigendum to "Positive integers divisible by the product of their nonzero digits", Portugaliae Math. 64 (2007), 1: 7585, Port. Math. 74 (2017), 169170.
James J. Tattersall, Elementary Number Theory in Nine Chapters (2005), 2nd Edition. p. 86 (see problems 4445).
Index entries for Colombian or self numbers and related sequences


MAPLE

filter:= proc(n)
local p;
p:= convert(convert(n, base, 10), `*`);
p <> 0 and n mod p = 0
end proc;
select(filter, [$1..10000]); # Robert Israel, Aug 24 2014


MATHEMATICA

zuckerQ[n_] := Module[{d = IntegerDigits[n], prod}, prod = Times @@ d; prod > 0 && Mod[n, prod] == 0]; Select[Range[5000], zuckerQ] (* Alonso del Arte, Aug 04 2004 *)


PROG

(Haskell)
import Data.List (elemIndices)
a007602 n = a007602_list !! (n1)
a007602_list = map succ $ elemIndices 1 $ map a188642 [1..]
 Reinhard Zumkeller, Apr 07 2011
(MAGMA) [ n: n in [1..2144]  not IsZero(&*Intseq(n)) and IsZero(n mod &*Intseq(n)) ]; // Bruno Berselli, May 28 2011
(Python)
from operator import mul
from functools import reduce
A007602 = [n for n in range(1, 10**5) if not (str(n).count('0') or n % reduce(mul, (int(d) for d in str(n))))] # Chai Wah Wu, Aug 25 2014
(PARI)
for(n=1, 10^5, d=digits(n); p=prod(i=1, #d, d[i]); if(p&&n%p==0, print1(n, ", "))) \\ Derek Orr, Aug 25 2014


CROSSREFS

Cf. A002796, A034709, A034838, A001103, A005349.
Cf. A286590 (for factorialbase analog).
Cf. A288069 (quotients).
Subsequence of A055471.
Sequence in context: A308472 A064700 A180484 * A337941 A167620 A169935
Adjacent sequences: A007599 A007600 A007601 * A007603 A007604 A007605


KEYWORD

nonn,base,easy


AUTHOR

N. J. A. Sloane, Mira Bernstein, Robert G. Wilson v


STATUS

approved



