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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A200521 Numbers n such that omega(n)=4 but bigomega(n)>4, i.e., having exactly 4 distinct prime factors, but at least one of these with multiplicity > 1. 3
 420, 630, 660, 780, 840, 924, 990, 1020, 1050, 1092, 1140, 1170, 1260, 1320, 1380, 1386, 1428, 1470, 1530, 1540, 1560, 1596, 1638, 1650, 1680, 1710, 1716, 1740, 1820, 1848, 1860, 1890, 1932, 1950, 1980, 2040, 2070, 2100, 2142, 2184, 2220, 2244 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS I expect that A123709(a(k))=32. LINKS M. F. Hasler, Table of n, a(n) for n = 1..18347 MATHEMATICA Select[Range[2500], PrimeNu[#] == 4 && PrimeOmega[#] > 4 &](* Jean-François Alcover, Jun 30 2013 *) PROG (PARI) is_A200521(n, c=4)={ omega(n)==c & bigomega(n)>c } CROSSREFS Cf. A200511, A178212. Sequence in context: A097822 A069064 A024410 * A189982 A070237 A305416 Adjacent sequences:  A200518 A200519 A200520 * A200522 A200523 A200524 KEYWORD nonn AUTHOR M. F. Hasler, Feb 09 2012 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 April 22 18:24 EDT 2021. Contains 343177 sequences. (Running on oeis4.)