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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. 1
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

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