This site is supported by donations to The OEIS Foundation.

 Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS". Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A165497 a(n) starts arithmetic progression of n terms separated by tau(a(n)), each term having the same number of divisors 2
 1, 3, 3, 60, 60, 201, 481, 5989, 3122037, 4434429, 13576837, 183894465, 187925171, 209072257, 1498642520, 12239200420, 20220712468, 20220712468, 875023683404, 992997544772, 2721798771116, 9770941874212, 9770941874212 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(15) > 10^9. a(19) > 10^11. - Donovan Johnson, Sep 24 2009 a(24) > 10^13. - Giovanni Resta, Aug 02 2013 LINKS EXAMPLE tau(60) = tau(72) = tau(84) = tau(96) = tau(108) = 12. This is the first such progression of length greater than 3, so a(4) and a(5) are both 60. PROG (PARI) has(n)=my(t=numdiv(n), s=1); while(numdiv(n+=t)==t, s++); s a(n)=my(k); while(has(k++)

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