The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A152617 Smallest number m such that m has exactly n distinct prime factors and sigma(m) has exactly n distinct prime factors. 0
 2, 6, 60, 1140, 22230, 778050, 28787850, 1237877550, 82937795850, 6054459097050, 802693813972050, 126022928793611850 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(13) <= 20541737393358731550. a(14) <= 3553720569051060558150. - Donovan Johnson, Jul 13 2011 LINKS Table of n, a(n) for n=1..12. EXAMPLE a(9) = 82937795850 = 2*3^2*5^2*7*13*19*37*43*67 (9 distinct prime factors). Sigma(82937795850) = 307906959360 = 2^11*3*5*7*11*13*17*19*31 (9 distinct prime factors). CROSSREFS Cf. A000203, A001221. Sequence in context: A338600 A089039 A156451 * A156472 A108640 A084971 Adjacent sequences: A152614 A152615 A152616 * A152618 A152619 A152620 KEYWORD nonn AUTHOR Donovan Johnson, Dec 13 2008 EXTENSIONS a(12) from Donovan Johnson, Jul 13 2011 STATUS approved

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

Last modified December 10 07:43 EST 2023. Contains 367699 sequences. (Running on oeis4.)