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A046460
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Number of prime factors of concatenation of numbers from 1 up to n, with multiplicity.
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10
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0, 3, 2, 2, 3, 8, 2, 5, 4, 3, 6, 6, 3, 3, 3, 4, 5, 6, 6, 10, 8, 6, 4, 6, 5, 9, 8, 7, 4, 7, 3, 6, 6, 2, 8, 9, 4, 4, 6, 9, 5, 7, 4, 7, 10, 7, 5, 8, 6, 10, 3, 9, 8, 14, 5, 5, 6, 4, 4, 8, 3, 8, 5, 10, 6, 8, 3, 10, 7, 6, 6, 7, 3, 9, 6, 6, 5, 6, 6, 10, 6, 7, 6, 7, 6
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Join[{1}, Table[PrimeOmega[FromDigits[Flatten[IntegerDigits[Range[i]]]]], {i, 2, 35}]] (* Jayanta Basu, Jun 02 2013 *)
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PROG
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(PARI) conc(n) = my(s=""); for(k=1, n, s=Str(s, k)); eval(s); \\ A007908
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CROSSREFS
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KEYWORD
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nonn,hard,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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