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Search: id:A095409
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| A095409 |
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Numbers n such that total number of decimal digits of all distinct prime factors of n is smaller than number of digits of n. |
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+0
3
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| 1, 16, 25, 27, 32, 49, 64, 81, 100, 108, 112, 121, 125, 128, 135, 144, 147, 160, 162, 169, 175, 189, 192, 196, 200, 216, 224, 225, 243, 245, 250, 256, 288, 289, 320, 324, 343, 361, 375, 384, 392, 400, 405, 432, 441, 448, 486, 500, 512, 529, 567, 576, 625, 640
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Solutions to A095407[x]<A055642[x].
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EXAMPLE
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n=100: prime set={2,5}, 3 digits and 2 digits of prime factors, so 100 is here;
n=147: prime set={3,7}, 3 digits and 2 digits of [ -factors, so 147 is here.
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MATHEMATICA
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ffi[x_] :=Flatten[FactorInteger[x]] lf[x_] :=Length[FactorInteger[x]] ba[x_] :=Table[Part[ffi[x], 2*j-1], {j, 1, lf[x]}] tdp[x_] :=Flatten[Table[IntegerDigits[Part[ba[x], j]], {j, 1, lf[x]}], 1] pl[x_] :=Length[tdp[x]] nl[x_] :=Length[IntegerDigits[x]] t1=Table[nl[w], {w, 1, 1000}]; t2=Table[pl[w], {w, 1, 1000}]; t2-t1 Flatten[Position[t2-t1, -1]]
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CROSSREFS
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Cf. A055642, A095407, A095408, A095410, A095411.
Sequence in context: A070571 A087622 A071524 this_sequence A111026 A124186 A001033
Adjacent sequences: A095406 A095407 A095408 this_sequence A095410 A095411 A095412
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KEYWORD
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base,nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jun 21 2004
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