A180126 - OEIS

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A180126

For numbers x >= a(n), PrimePi(n,x) > PrimePi(n-1,x), where PrimePi(n,x) is the number of n-almost prime numbers <= x.

3, 34, 15530, 151165607042 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`Note that a(n) is an n-almost prime. An n-almost prime is a number having exactly n prime factors (counted with multiplicity). So 1 is the only 0-almost prime; 1-almost primes are the usual prime numbers; 2-almost primes are also called semiprimes. The first three terms are mentioned in A125149.`
	LINKS	`Table of n, a(n) for n=1..4.`
	CROSSREFS	`Sequence in context: A194892 A182382 A222787 * A214854 A054287 A176761` `Adjacent sequences: A180123 A180124 A180125 * A180127 A180128 A180129`
	KEYWORD	`bref,hard,more,nonn`
	AUTHOR	`T. D. Noe, Aug 11 2010`
	STATUS	`approved`

Last modified January 17 17:33 EST 2021. Contains 340247 sequences. (Running on oeis4.)