id:A073425 - OEIS Search Results

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Number of primes not exceeding n-th composite number.

+0
5

2, 3, 4, 4, 4, 5, 6, 6, 6, 7, 8, 8, 8, 9, 9, 9, 9, 9, 10, 11, 11, 11, 11, 11, 12, 12, 12, 13, 14, 14, 14, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 17, 18, 18, 18, 18, 18, 19, 19, 19, 20, 21, 21, 21, 21, 21, 22, 22, 22, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 25, 25, 25, 26 (list; graph; listen)

	OFFSET	`1,1`
	FORMULA	`a(n)=A000720[A002808(n)]`
	EXAMPLE	`n=100: composite[100]=133,Pi[133]=32=a(100)`
	MATHEMATICA	`c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Table[PrimePi[c[w]], {w, 1, 128}]`
	CROSSREFS	`Cf. A065890, A073426, A000720, A002808.` `Sequence in context: A003160 A060740 A123273 this_sequence A087876 A006158 A135414` `Adjacent sequences: A073422 A073423 A073424 this_sequence A073426 A073427 A073428`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu), Jul 31 2002`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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