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Search: id:A120122
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| A120122 |
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Numbers n such that n=phi(d_1*d_2*...*d_k)*(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 the sequences A120121 & A120123, 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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24 is in the sequence because 24=phi(2*4)*(2+4).
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MATHEMATICA
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Do[If[h = IntegerDigits[n]; l = Length[h]; n == EulerPhi[ Product[h[[k]], {k, l}]]*Sum[h[[k]], {k, l}], Print[n]], {n, 100000000}]
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CROSSREFS
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Cf. A120121, A120123.
Sequence in context: A000722 A098679 A123851 this_sequence A068943 A100815 A159932
Adjacent sequences: A120119 A120120 A120121 this_sequence A120123 A120124 A120125
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KEYWORD
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base,fini,nonn
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AUTHOR
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Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 12 2006
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