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A068572 Numbers n such that sigma(n) = product of the squares of the decimal digits of n. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
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
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

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Last modified June 20 09:16 EDT 2024. Contains 373515 sequences. (Running on oeis4.)