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!)
A275377 Number of odd prime factors (with multiplicity) of generalized Fermat number 3^(2^n) + 1. 4
0, 1, 1, 2, 1, 1, 1, 5, 4, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
Arkadiusz Wesolowski, A 93-digit prime factor of b(9)
FORMULA
a(n) = A001222(A059919(n)) - 1 for n > 0. - Felix Fröhlich, Jul 25 2016
EXAMPLE
b(n) = (3^(2^n) + 1)/2.
Complete Factorizations
b(0) = 2
b(1) = 5
b(2) = 41
b(3) = 17*193
b(4) = 21523361
b(5) = 926510094425921
b(6) = 1716841910146256242328924544641
b(7) = 257*275201*138424618868737*3913786281514524929*P21
b(8) = 12289*8972801*891206124520373602817*P90
b(9) = 134382593*22320686081*12079910333441*100512627347897906177*P93*P101
PROG
(PARI) a001222(n) = bigomega(n)
a059919(n) = 3^(2^n)+1
a(n) = if(n==0, 0, a001222(a059919(n))-1) \\ Felix Fröhlich, Jul 25 2016
CROSSREFS
Sequence in context: A227578 A181783 A121395 * A219585 A292464 A090628
KEYWORD
nonn,hard,more
AUTHOR
EXTENSIONS
a(9) was found in 2008 by Tom Womack
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 22:09 EDT 2024. Contains 370951 sequences. (Running on oeis4.)