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

1,2

Links

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

Example

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

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 *)

Crossrefs

Cf. A058627.

Sequence in context: A216444 A083428 A183780 * A236897 A163589 A250582

Adjacent sequences: A068569 A068570 A068571 * A068573 A068574 A068575

Keyword

nonn,base

Author

Joseph L. Pe, Mar 26 2002

Extensions

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

Status

approved