Lucas cofactor

The Prime Pages keeps a list of the 5000 largest known primes, plus a few each of certain selected archivable forms and classes. These forms are defined in this collection's home page.

This page is about one of those forms.

(up) Definitions and Notes

The Lucas numbers can be defined as follows:
v1 = 1, v2 = 3 and vn+1 = vn + vn-1 (n > 2)

It can be shown that, for odd m, vn divides vnm

In the same way that we defined a Mersenne cofactor, we define a Lucas cofactor to be a proper divisor of a Lucas number with a prime index.

(up) Record Primes of this Type

rankprime digitswhowhencomment
1V(91943)/551659 / 2390519 / 9687119153094919 19187 E1 Jul 2022 Lucas cofactor, ECPP
2V(91873)/3674921 / 193484539 / 167745030829 19175 E1 Jul 2022 Lucas cofactor, ECPP
3V(86477)/1042112515940998434071039 18049 c77 Sep 2020 Lucas cofactor, ECPP
4V(80761)/(23259169 · 24510801979) 16861 c77 Aug 2020 Lucas cofactor, ECPP
5V(77417)/313991497376559420151 16159 c77 Aug 2020 Lucas cofactor, ECPP
6V(68213)/7290202116115634431 14237 c77 Aug 2018 Lucas cofactor, ECPP
7V(66533)/2128184670585621839884209100279 13875 c77 Dec 2018 Lucas cofactor, ECPP
8V(52859)/1124137922466041911 11029 c8 Oct 2014 Lucas cofactor, ECPP
10857 c8 Mar 2015 Lucas cofactor, ECPP
10V(52009)/39772636393178951550299332730909 10838 c8 Mar 2015 Lucas cofactor, ECPP
10789 c8 Jan 2015 Lucas cofactor, ECPP
12V(51349)/224417260052884218046541 10708 c8 Sep 2014 Lucas cofactor, ECPP
13V(50989)/69818796119453411 10640 c8 Aug 2014 Lucas cofactor, ECPP
14V(49391)/298414424560419239 10305 c8 Jun 2013 Lucas cofactor, ECPP
15V(45953)/4561241750239 9591 c56 Mar 2012 Lucas cofactor, ECPP
16V(43987)/175949 9188 c8 May 2014 Lucas cofactor, ECPP
17V(39769)/18139109172816581 8295 c8 Nov 2013 Lucas cofactor, ECPP
18V(39607)/158429 8273 c46 Dec 2011 Lucas cofactor, ECPP
19V(37357)/20210113386303842894568629 7782 c8 Sep 2013 Lucas cofactor, ECPP
20V(35107)/525110138418084707309 7317 c8 Sep 2013 Lucas cofactor, ECPP

(up) References

J. Brillhart, P. Montgomery and R. Silverman, "Tables of Fibonacci and Lucas factorizations," Math. Comp., 50 (1988) 251--260.  MR 89h:11002
H. Dubner and W. Keller, "New Fibonacci and Lucas primes," Math. Comp., 68 (1999) 417--427.  MR 99c:11008 [A supplement gives the complete factorization of Fn and Ln for n>1000 whenever it is known.]
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