A055037 - OEIS

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A055037

Number of numbers <= n with an even number of prime factors (counted with multiplicity).

1, 1, 1, 2, 2, 3, 3, 3, 4, 5, 5, 5, 5, 6, 7, 8, 8, 8, 8, 8, 9, 10, 10, 11, 12, 13, 13, 13, 13, 13, 13, 13, 14, 15, 16, 17, 17, 18, 19, 20, 20, 20, 20, 20, 20, 21, 21, 21, 22, 22, 23, 23, 23, 24, 25, 26, 27, 28, 28, 29, 29, 30, 30, 31, 32, 32, 32, 32, 33, 33, 33, 33, 33, 34, 34, 34 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,4`
	LINKS	`Eric Weisstein's World of Mathematics, Polya Conjecture`
	FORMULA	`1/2Sum_{k=1..n} (1+lambda(k))= (1/2) (n+L(n)), where lambda(n)=A008836(n) and L(n)=A002819(n).`
	CROSSREFS	`Cf. A001222.` `Sequence in context: A080677 A153112 A005350 * A125186 A140473 A115384` `Adjacent sequences: A055034 A055035 A055036 * A055038 A055039 A055040`
	KEYWORD	`nonn`
	AUTHOR	`Antreas P. Hatzipolakis (xpolakis(AT)otenet.gr), Jun 01 2000`
	EXTENSIONS	`Formula and more terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 03 2001`

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Last modified February 16 03:44 EST 2012. Contains 205860 sequences.