id:A055399 - OEIS Search Results

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Stages of sieve of Eratosthenes needed to identify n as prime or composite.

+0
6

1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 3, 1, 2, 1, 3, 1, 3, 1, 2, 1, 3, 1, 3, 1, 2, 1, 4, 1, 4, 1, 2, 1, 3, 1, 4, 1, 2, 1, 4, 1, 4, 1, 2, 1, 4, 1, 4, 1, 2, 1, 5, 1, 3, 1, 2, 1, 5, 1, 5, 1, 2, 1, 3, 1, 5, 1, 2, 1, 5, 1, 5, 1, 2, 1, 4, 1, 5, 1, 2, 1, 5, 1, 3, 1, 2, 1, 5, 1, 4, 1, 2, 1, 3, 1, 5, 1, 2, 1, 5, 1, 5, 1, 2, 1, 5 (list; graph; listen)

	OFFSET	`3,3`
	LINKS	`H. B. Meyer, Eratosthenes' sieve` `J. Britton, Sieve of Eratosthenes Applet` `C. K. Caldwell, The Prime Glossary, sieve of Eratosthenes`
	FORMULA	`If n is composite, a(n)=A055396(n); if n is prime, a(n)=A000040(firstprimeabove(sqrt(n))`
	EXAMPLE	`a(7)=2 because 7 is not removed by the first two stages of the sieve, but is less than the square of the second prime (though not the square of the first); a(35)=3 because 35 is removed in the third stage as a multiple of 5.`
	CROSSREFS	`Cf. A000040, A002808, A004280, A038179, A055396, A055397, A055397.` `Cf. A054403; A055398; A083269.` `Adjacent sequences: A055396 A055397 A055398 this_sequence A055400 A055401 A055402` `Sequence in context: A045778 A033103 A060775 this_sequence A029426 A085342 A025825`
	KEYWORD	`nice,nonn`
	AUTHOR	`Henry Bottomley (se16(AT)btinternet.com), May 15 2000`

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Last modified October 12 15:26 EDT 2008. Contains 144830 sequences.

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