login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A071147 Smallest squarefree number k with exactly n prime factors such that the sum the prime factors is divisible by the largest prime dividing k, or 0 if no such k exists. 8
1, 2, 0, 30, 3135, 3570, 72930, 1231230, 14804790, 497668710, 14908423530, 278196808890, 12192694624110, 550939666387110, 21275256232500270, 1458502323630662310, 87988283090327810190, 3254611619240885033130, 261462818462495728868790, 9965666894849284108299810, 557940830126698960967415390, 90544636506979071680577724410 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

No solution exists for n=2, so a(2)=0.

LINKS

Table of n, a(n) for n=0..21.

FORMULA

A008472(k)/A006530(k) is integer; k is squarefree and has exactly n prime factors.

EXAMPLE

a(0) =       1 = 1;

a(1) =       2 = 2;

a(3) =      30 = 2 *  3 *  5;

a(4) =    3135 = 3 *  5 * 11 * 19;

a(5) =    3570 = 2 *  3 *  5 *  7 * 17;

a(6) =   72930 = 2 *  3 *  5 * 11 * 13 * 17;

a(7) = 1231230 = 2 *  3 *  5 *  7 * 11 * 13 * 41.

CROSSREFS

Cf. A008472, A006530, A000961, A025475, A037074, A071139-A071146.

Sequence in context: A092177 A104466 A086487 * A156481 A176726 A156452

Adjacent sequences:  A071144 A071145 A071146 * A071148 A071149 A071150

KEYWORD

nonn

AUTHOR

Labos Elemer, May 13 2002

EXTENSIONS

Corrected and extended by Donovan Johnson, Apr 22 2008

Name corrected by Jon E. Schoenfield, Jul 08 2018

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 20 06:04 EDT 2019. Contains 326139 sequences. (Running on oeis4.)