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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

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

Cf. A000720, A005408.

Sequence in context: A088524 A129337 A133909 * A206913 A117767 A293701

Adjacent sequences:  A177688 A177689 A177690 * A177692 A177693 A177694

KEYWORD

nonn,easy

AUTHOR

Giovanni Teofilatto, May 11 2010

EXTENSIONS

Erroneous formula removed by R. J. Mathar, May 14 2010

STATUS

approved

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Last modified October 26 17:32 EDT 2020. Contains 338027 sequences. (Running on oeis4.)