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Search: id:A120123
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| A120123 |
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Numbers n such that n=(d_1*d_2*...*d_k)*phi(d_1+d_2+...+d_k) where d_1 d_2... d_k is the decimal expansion of n. |
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3
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OFFSET
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1,2
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COMMENT
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Conjecture: 139968 is the largest term. Except for the first term, all terms are even. 139968 is also in A120121 & A120122, so it has a very pleasant property (see the Comments lines of A120121).
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LINKS
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Prime Curios, 139968.
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EXAMPLE
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34992 is in the sequence because 34992=(3*4*9*9*2)*phi(3+4+9+9+2).
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MATHEMATICA
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Do[If[h = IntegerDigits[n]; l = Length[h]; n == Product[h[[k]], {k, l}]*EulerPhi[Sum[h[[k]], {k, l}]], Print[n]], {n, 50000000}]
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CROSSREFS
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Cf. A120121, A120122.
Sequence in context: A134796 A120830 A079195 this_sequence A140014 A106301 A127623
Adjacent sequences: A120120 A120121 A120122 this_sequence A120124 A120125 A120126
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KEYWORD
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base,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 12 2006
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