%I #24 May 22 2022 19:51:39
%S 1,3,2,5,3,5,2,7,3,6,3,8,2,5,5,10,3,8,3,10,4,7,3,11,5,5,6,9,4,11,4,12,
%T 5,8,6,12,3,7,7,13,4,11,3,11,9,6,5,17,7,10,6,9,4,13,8,13,7,9,3,17,3,8,
%U 6,14,7,12,4,12,6,11,2,16,5,8,10,11,7,15,4,18,9,8,5,18,7,6,8,16,4,19,5
%N Number of prime factors of 3^n - 1 (counted with multiplicity).
%H Max Alekseyev, <a href="/A057958/b057958.txt">Table of n, a(n) for n = 1..690</a> (first 660 terms from Amiram Eldar)
%H S. S. Wagstaff, Jr., <a href="https://homes.cerias.purdue.edu/~ssw/cun/index.html">The Cunningham Project</a>
%F Mobius transform of A085028. - _T. D. Noe_, Jun 19 2003
%F a(n) = A001222(A024023(n)). - _Amiram Eldar_, Feb 01 2020
%o (PARI) a(n)=bigomega(3^n-1) \\ _Charles R Greathouse IV_, Sep 14 2015
%Y bigomega(b^n-1): A057951 (b=10), A057952 (b=9), A057953 (b=8), A057954 (b=7), A057955 (b=6), A057956 (b=5), A057957 (b=4), this sequence (b=3), A046051 (b=2).
%Y Cf. A001222, A024023, A085028, A002591 A074477, A057952, A133801, A274909.
%K nonn
%O 1,2
%A _Patrick De Geest_, Nov 15 2000
%E Offset corrected by _Amiram Eldar_, Feb 01 2020