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A177691
The odd values of PrimePi(.), with repetition.
1
1, 3, 3, 5, 5, 7, 7, 9, 9, 9, 9, 9, 9, 11, 11, 11, 11, 11, 11, 13, 13, 15, 15, 15, 15, 15, 15, 17, 17, 19, 19, 19, 19, 21, 21, 21, 21, 21, 21, 23, 23, 23, 23, 23, 23, 25, 25, 25, 25, 27, 27, 27, 27, 29, 29, 29, 29, 31, 31, 31, 31, 33, 33, 35, 35, 37, 37, 37, 37, 37, 37, 39, 39, 39
OFFSET
1,2
LINKS
FORMULA
Obtained by removing all even numbers from A000720. Block lengths (frequencies of repetitions) are in A078584.
MAPLE
seq((2*n-1)$(ithprime(2*n)-ithprime(2*n-1)), n=1..30); # Robert Israel, Feb 13 2019
MATHEMATICA
Select[PrimePi[Range[300]], OddQ] (* Harvey P. Dale, Dec 24 2014 *)
CROSSREFS
Sequence in context: A088524 A129337 A133909 * A206913 A117767 A340836
KEYWORD
nonn,easy
AUTHOR
Giovanni Teofilatto, May 11 2010
EXTENSIONS
Erroneous formula removed by R. J. Mathar, May 14 2010
STATUS
approved