A113913 Number of distinct prime factors of 3^(3^n)+1.

1, 2, 4, 6, 11, 20, 27

Offset: 0

Author

Jorge Coveiro, Jan 29 2006

Keywords

• hard
• more
• nonn

Comments

The term omega(3^(3^6)+1) was obtained with ECM factoring.

Programs

Mathematica

Table[PrimeNu[3^(3^n) + 1], {n,1,10}] (* G. C. Greubel, May 16 2017 *)

PARI

for(x=1,6,print1( omega(3^(3^x)+1),","))

Formula

a(n) = A001221(A129290(n)).