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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A031440 a(0)=3 and for n>0 a(n) is the greatest prime factor of a(n-1)^2 - 2. 2

%I

%S 3,7,47,2207,4481,26111,189017,67271,11815633,606737,708641,354023,

%T 125332284527,51939720282500417,18062107820423,1376080289340623571113,

%U 4012316132900773615751,983669740542169,4443427285129103,19744046038229790810567377584607,4300749014896245437702886338812998834884967953,41572359968343362282287450730112204489086145685200294134959430572332688727999

%N a(0)=3 and for n>0 a(n) is the greatest prime factor of a(n-1)^2 - 2.

%C Is this sequence unbounded? [_Charles R Greathouse IV_, Dec 29 2011]

%H Dennis Langdeau, <a href="/A031440/b031440.txt">Table of n, a(n) for n = 0..23</a>

%t NestList[FactorInteger[#^2-2][[-1,1]]&,3,22] (* _Harvey P. Dale_, Jan 10 2013 *)

%K nonn,nice

%O 0,1

%A _Yasutoshi Kohmoto_

%E More terms from Dennis Langdeau (dlangdea(AT)sfu.ca), Jun 26 2006

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 November 19 22:34 EST 2019. Contains 329323 sequences. (Running on oeis4.)