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Numbers n such that n / product of digits of n is a square.
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%I #12 May 09 2019 09:21:06

%S 1,2,3,4,5,6,7,8,9,135,144,384,1575,1715,6144,6912,11664,14112,16224,

%T 18816,23328,26136,31212,41616,82944,83232,93312,131424,131712,186624,

%U 248832,371112,1168128,2214144,2239488,2333772,3321216,3881472,6642432

%N Numbers n such that n / product of digits of n is a square.

%t Select[Range[665*10^4],IntegerQ[Sqrt[#/Times@@IntegerDigits[#]]]&]// Quiet (* _Harvey P. Dale_, May 09 2019 *)

%o (PARI) isok(n) = {digs = digits(n); q = prod(i=1, #digs, digs[i]); (q != 0) && (n % q == 0) && issquare(n/q);} \\ _Michel Marcus_, Sep 04 2013

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_, Bill Moran (moran1(AT)llnl.gov)