id:A060208 - OEIS Search Results

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2Pi(n) - Pi(2n), where Pi is A000720.

+0
5

-1, 0, 1, 0, 2, 1, 2, 2, 1, 0, 2, 1, 3, 3, 2, 1, 3, 3, 4, 4, 3, 2, 4, 3, 3, 3, 2, 2, 4, 3, 4, 4, 4, 3, 3, 2, 3, 3, 3, 2, 4, 3, 5, 5, 4, 4, 6, 6, 5, 5, 4, 3, 5, 4, 3, 3, 2, 2, 4, 4, 6, 6, 6, 5, 5, 4, 6, 6, 5, 4, 6, 6, 8, 8, 7, 6, 6, 6, 7, 7, 7, 6, 8, 7, 7, 7, 6, 6, 8, 7, 6, 6, 6, 6, 6, 5, 6, 6, 5, 4, 6, 6, 8, 8, 8, 7, 9, 9, 11, 11, 11, 10, 12, 11, 10, 10, 9, 9, 9, 8, 7, 7 (list; graph; listen)

	OFFSET	`1,5`
	REFERENCES	`S. Segal, On Pi(x+1)<=Pi(x)+Pi(y). Transactions American Mathematical Society, 104 (1962), 523-527.`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..10000` `E. Labos, Illustration`
	FORMULA	`a(n) = Mod[2PrimePi[n], PrimePi[2n]] = 2A000720(n)-A000720(2n) for n>1.` `a(n) ~ 2n log 2 / (log n)^2, by the prime number theorem. - njas, Mar 12 2007` `a(n) = -A047886(n,n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Apr 15 2008`
	EXAMPLE	`n=100, Pi(100)=25, Pi(200)=46, 2Pi(100)-Pi(2100) =4=a(100)`
	CROSSREFS	`Cf. A060207, A007097, A000720, A033844.` `Sequence in context: A127249 A127251 A063251 this_sequence A004570 A071429 A109672` `Adjacent sequences: A060205 A060206 A060207 this_sequence A060209 A060210 A060211`
	KEYWORD	`sign`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Mar 19 2001`

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Last modified July 25 07:41 EDT 2008. Contains 142293 sequences.

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