The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 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

%I

%S 0,1,1,2,1,1,1,5,4,6

%N Number of odd prime factors (with multiplicity) of generalized Fermat number 3^(2^n) + 1.

%H Arkadiusz Wesolowski, <a href="/A275377/a275377.txt">A 93-digit prime factor of b(9)</a>

%F a(n) = A001222(A059919(n)) - 1 for n > 0. - _Felix FrÃ¶hlich_, Jul 25 2016

%e b(n) = (3^(2^n) + 1)/2.

%e Complete Factorizations

%e b(0) = 2

%e b(1) = 5

%e b(2) = 41

%e b(3) = 17*193

%e b(4) = 21523361

%e b(5) = 926510094425921

%e b(6) = 1716841910146256242328924544641

%e b(7) = 257*275201*138424618868737*3913786281514524929*P21

%e b(8) = 12289*8972801*891206124520373602817*P90

%e b(9) = 134382593*22320686081*12079910333441*100512627347897906177*P93*P101

%o (PARI) a001222(n) = bigomega(n)

%o a059919(n) = 3^(2^n)+1

%o a(n) = if(n==0, 0, a001222(a059919(n))-1) \\ _Felix FrÃ¶hlich_, Jul 25 2016

%Y Cf. A059919, A273945.

%K nonn,hard,more

%O 0,4

%A _Arkadiusz Wesolowski_, Jul 25 2016

%E a(9) was found in 2008 by Tom Womack

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.

Last modified May 13 06:04 EDT 2021. Contains 343836 sequences. (Running on oeis4.)