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A111185
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Let f(k) denote the largest prime factor of k which is not a palindrome. Sequence gives numbers k such that the sum of the factorials of the digits of k is equal to f(k) reversed.
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1
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143, 541, 2105, 2444, 3431, 4144, 4233, 4301, 4440, 10234, 12243, 12341, 20313, 22320, 30422, 34030, 34144, 35140, 46003, 52100, 53013, 102613, 106312, 112413, 113162, 120032, 134046, 200340, 202124, 203112, 210304, 211203, 211232, 212004
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OFFSET
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1,1
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LINKS
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EXAMPLE
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2105 = 5*'421' and 2! + 1! + 0! + 5! = 124.
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MATHEMATICA
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r[n_] := FromDigits[Reverse[IntegerDigits[n]]]; np[n_] := (n != r[n]); f[n_] := Plus @@ Map[ #!&, IntegerDigits[n]]; Do[l = Select[First /@ FactorInteger[n], np]; If[Length[l] > 0, k = r[Max[l]]; If[k == f[n], Print[n]]], {n, 1, 10^6}] (* Ryan Propper, Oct 19 2005 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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