|
| |
|
|
A081173
|
|
a(1) = 2, then a(n) = greatest prime factor of a(n-1)^2+2.
|
|
2
| |
|
|
2, 3, 11, 41, 17, 97, 3137, 13499, 60741001, 14158633, 7424699571433, 18375387908679124623224497, 152868746152697352174823427, 114585848725150699093848122619332057, 2117552824725684501808097956698634897, 34759922213207174486822944687721824905112848905750167403101021576017059, 57191433705834025254780615830990723253902440879104281100230506839641
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
REFERENCES
| Teske, Edlyn and Williams, Hugh C., A note on Shanks's chains of primes, in Algorithmic number theory (Leiden, 2000), 563-580, Lecture Notes in Comput. Sci., 1838, Springer, Berlin, 2000.
|
|
|
LINKS
| Dennis Langdeau, Table of n, a(n) for n = 1..20
|
|
|
EXAMPLE
| a(2) = 3 because 3 is greatest prime factor of 2^2+2. a(3)=11 because 3^2+2 is prime.
|
|
|
MATHEMATICA
| a[1]=2; a[n_] := a[n]=FactorInteger[a[n-1]^2+2][[ -1, 1]]
|
|
|
CROSSREFS
| Cf. A083388
Sequence in context: A007756 A000280 A046224 * A179266 A055692 A051075
Adjacent sequences: A081170 A081171 A081172 * A081174 A081175 A081176
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Donald S. McDonald (don.mcdonald(AT)paradise.net.nz), Apr 17 2003
|
|
|
EXTENSIONS
| More terms from Donald S. McDonald (don.mcdonald(AT)paradise.net.nz), Apr 20 2003, Robert G. Wilson v (rgwv(AT)rgwv.com) and Dean Hickerson (dean.hickerson(AT)yahoo.com), Apr 22 2003
More terms from Dennis Langdeau (dlangdea(AT)sfu.ca), Jun 18 2006
|
| |
|
|
