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

1, 1426, 2235, 13462, 45192, 67512, 95241, 119186, 134732, 152434, 165271, 263351, 541443, 1424335, 2316354, 2341535, 2521376, 3263541, 3265218, 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

Offset: 1

Author

Joseph L. Pe, Mar 26 2002

Keywords

• nonn
• base

Examples

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

Links

• Giovanni Resta, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A058627.

Programs

Mathematica

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}]
Select[Range[25*10^6],DivisorSigma[1,#]==(Times@@IntegerDigits[#])^2&] (* Harvey P. Dale, Aug 29 2014 *)

Extensions

Added missing first term and a(14)-a(48) from Donovan Johnson, Nov 20 2010