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A065719
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Number of 8's in decimal expansion of 2^n.
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13
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0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 2, 1, 0, 0, 4, 0, 0, 2, 1, 1, 1, 1, 2, 0, 2, 2, 2, 1, 1, 1, 4, 0, 0, 1, 2, 1, 4, 1, 3, 1, 0, 2, 3, 0, 0, 4, 3, 0, 4, 2, 2, 1, 1, 3, 3, 1, 3, 3, 2, 2, 2, 1, 4, 2, 0, 7, 3, 1, 4, 0, 4, 2, 2, 5, 1, 4, 3, 1, 1, 4, 1, 3, 6, 1, 1, 7, 3, 1, 5, 1, 4, 1
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OFFSET
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0,20
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COMMENTS
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2^7 = 128 so a(7)=1.
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LINKS
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MATHEMATICA
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Table[ Count[ IntegerDigits[2^n], 8], {n, 0, 100} ]
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PROG
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(PARI) Count(x, d)= { local(c=0, f); while (x>9, f=x-10*(x\10); if (f==d, c++); x\=10); if (x==d, c++); return(c) }
{ for (n=0, 1000, a=Count(2^n, 8); write("b065719.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 27 2009
(PARI) a(n) = #select(x->(x==8), 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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