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A101639
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Positive integers n for which n = f(n), where f(n) is the total number of 2's required when writing out all numbers between 0 and n.
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13
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28263827, 35000000, 242463827, 500000000, 528263827, 535000000, 10000000000, 10028263827, 10035000000, 10242463827, 10500000000, 10528263827, 10535000000
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OFFSET
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1,1
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COMMENTS
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Related to a problem posed by Google and discussed on the MathWorld link.
This is the complete list of all 13 positive numbers n such that n is equal to the number of 2's in the decimal digits of all numbers <= n. - Daniel Hirschberg (dan(AT)ics.uci.edu), May 05 2007
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LINKS
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EXAMPLE
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a(1) = 28263827 since writing out all numbers from 0 to 28263827 requires that 28263827 2's be used and since 28263827 is the first such positive integer.
a(4) = 500000000 because the number of 2's in the decimal digits of the numbers from 1 to 500000000 is 500000000 and this is the 4th such number.
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CROSSREFS
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KEYWORD
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nonn,base,fini,full
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AUTHOR
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EXTENSIONS
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More terms from Daniel Hirschberg (dan(AT)ics.uci.edu), May 05 2007
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STATUS
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approved
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