The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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