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 A068572 Numbers n such that sigma(n) = product of the squares of the decimal digits of n. 3

%I

%S 1,1426,2235,13462,45192,67512,95241,119186,134732,152434,165271,

%T 263351,541443,1424335,2316354,2341535,2521376,3263541,3265218,

%U 3341572,3652182,4214295,4225417,5147324,5232472,6442513,11454724,11765416,11976314,12354716,12623752,13181665,13322745,13416198,14135891,14235642,14513891,16126734,16542361,17163642,17235714,18257331,18333451,19346152,21352862,21544941,21743524,23187129

%N Numbers n such that sigma(n) = product of the squares of the decimal digits of n.

%H Giovanni Resta, <a href="/A068572/b068572.txt">Table of n, a(n) for n = 1..1000</a>

%e sigma(541443) = 921600 = 5^2 * 4^2 * 1^2 *4^2* 4^2 *3^2, so 541443 is a term of the sequence.

%t f[n_] := Module[{a, l}, a = IntegerDigits[n]; l = Length[a]; Product[a[[i]], {i, 1, l}]^2]; Do[If[f[n] == DivisorSigma[1, n], Print[n]], {n, 2, 10^6}]

%t Select[Range[25*10^6],DivisorSigma[1,#]==(Times@@IntegerDigits[#])^2&] (* _Harvey P. Dale_, Aug 29 2014 *)

%Y Cf. A058627.

%K nonn,base

%O 1,2

%A _Joseph L. Pe_, Mar 26 2002

%E Added missing first term and a(14)-a(48) from _Donovan Johnson_, Nov 20 2010

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Last modified September 23 12:06 EDT 2021. Contains 347616 sequences. (Running on oeis4.)