This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A014946 Numbers n such that n divides 6^n-1. 15
 1, 5, 25, 125, 625, 1555, 3125, 7775, 15625, 38875, 78125, 194375, 390625, 483605, 971875, 1953125, 2418025, 4859375, 9673655, 9765625, 12090125, 24296875, 48368275, 48828125, 60450625, 120909025, 121484375, 150401155, 241841375 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Includes all powers of 5. If a term such as 1555 = 5*311 occurs, so does any number of the form 5^a * 311^b for a>3. Contribution from Alexander Adamchuk, May 16 2010: (Start) All terms that are not the powers of 5 are divisible by 5 and 311. Prime divisors of a(n) are {5, 311, 6221 , 15551, 155501, ...}. (End) LINKS MATHEMATICA Select[ Range[ 5*10^7], PowerMod[6, #, # ] == 1 & ] PROG (PARI) is(n)=Mod(6, n)^n==1 \\ Charles R Greathouse IV, Nov 04 2016 CROSSREFS Sequence in context: A250357 A216125 A057831 * A188580 A132839 A206451 Adjacent sequences:  A014943 A014944 A014945 * A014947 A014948 A014949 KEYWORD nonn AUTHOR EXTENSIONS Better description from Benoit Cloitre, Mar 06 2002 Edited and extended by Robert G. Wilson v, Jun 18 2002 a(25)-a(45) from Alexander Adamchuk, May 16 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 December 9 19:51 EST 2019. Contains 329879 sequences. (Running on oeis4.)