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A065716
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Number of 5's in decimal expansion of 2^n.
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11
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 1, 1, 1, 0, 0, 0, 2, 0, 0, 2, 1, 0, 0, 0, 2, 0, 1, 0, 1, 0, 3, 1, 4, 1, 0, 1, 1, 0, 2, 1, 2, 1, 2, 2, 1, 1, 0, 2, 4, 1, 2, 2, 2, 0, 2, 2, 0, 0, 3, 5, 5, 1, 0, 1, 1, 3, 2, 4, 3, 3, 2, 1, 3, 3, 2, 1, 3, 4, 4, 3, 1, 1, 3, 4, 1, 3, 2, 4, 5, 5, 2, 2
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OFFSET
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0,17
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LINKS
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EXAMPLE
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2^8 = 256 so a(8)=1.
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MATHEMATICA
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Table[ Count[ IntegerDigits[2^n], 5], {n, 0, 100} ]
DigitCount[#, 10, 5]&/@(2^Range[0, 100]) (* Harvey P. Dale, Nov 13 2021 *)
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PROG
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(PARI) a(n) = #select(x->(x==5), digits(2^n)); \\ Michel Marcus, Jun 15 2018
(Python)
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CROSSREFS
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KEYWORD
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nonn,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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