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A104638
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Number of odd digits in n-th prime.
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4
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0, 1, 1, 1, 2, 2, 2, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 2, 3, 2, 3, 3, 3, 2, 3, 3, 2, 2, 3, 3, 2, 3, 3, 3, 3, 2, 1, 1, 1, 2, 2, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 3, 3, 3, 3, 3, 2, 2, 3, 3, 2, 3, 3, 2, 2, 3, 1, 1, 2, 1, 2, 2, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2
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OFFSET
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1,5
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COMMENTS
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The only zero is the first term. Sequence is unbounded. - Zak Seidov, Jan 12 2016
For any N, the asymptotic density of terms >= N is 1.
On the other hand, a(n) = 2 if prime(n) is in A159352, which is conjectured to be infinite.
Record values: a(2) = 1, a(5) = 2, a(30) = 3, a(187) = 4, a(1346) = 5, a(10545) = 6, a(86538) = 7, a(733410) = 8.
(End)
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LINKS
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FORMULA
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MAPLE
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seq(nops(select(type, convert(ithprime(i), base, 10), odd)), i=1..100); # Robert Israel, Jan 12 2016
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MATHEMATICA
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Table[Count[IntegerDigits[Prime[n]], _?OddQ], {n, 100}] (* Harvey P. Dale, Jan 22 2012 *)
Table[Total[Mod[IntegerDigits[Prime[n]], 2]], {n, 100}] (* Vincenzo Librandi, Jan 13 2016 *)
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PROG
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(PARI) a(n)=vecsum(digits(prime(n)%2)) \\ Zak Seidov, Jan 12 2016
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CROSSREFS
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KEYWORD
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easy,nonn,base
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AUTHOR
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STATUS
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approved
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