login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A275379 Number of prime factors (with multiplicity) of generalized Fermat number 6^(2^n) + 1. 3
1, 1, 1, 2, 3, 3, 3, 7, 3, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
FORMULA
a(n) = A001222(A078303(n)). - Felix Fröhlich, Jul 25 2016
EXAMPLE
b(n) = 6^(2^n) + 1.
Complete Factorizations
b(0) = 7
b(1) = 37
b(2) = 1297
b(3) = 17*98801
b(4) = 353*1697*4709377
b(5) = 2753*145601*19854979505843329
b(6) = 4926056449*447183309836853377*28753787197056661026689
b(7) = 257*763649*50307329*3191106049*2339340566463317436161*
2983028405608735541756929*18247770097021321924017185281
b(8) = 18433*
69615986569139423375849495295909549956813828853888948633601*P137
b(9) = 80897*3360769*12581314681802812884728041373153281*
3513902440204553274892072241244613302018049*P311
MATHEMATICA
Table[PrimeOmega[6^(2^n) + 1], {n, 0, 6}] (* Michael De Vlieger, Jul 26 2016 *)
PROG
(PARI) a(n) = bigomega(factor(6^(2^n)+1))
CROSSREFS
Sequence in context: A170895 A141479 A055081 * A109833 A132005 A088041
KEYWORD
nonn,hard,more
AUTHOR
EXTENSIONS
a(8) was found in 2001 by Robert Silverman
a(9) was found in 2007 by Nestor de Araújo Melo
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)