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Number of prime factors of 9^n - 1 (counted with multiplicity).
17

%I #34 Jan 07 2024 13:30:35

%S 3,5,5,7,6,8,5,10,8,10,7,11,5,9,11,12,8,12,7,13,11,11,6,17,10,9,13,13,

%T 9,17,8,14,12,12,11,16,8,11,15,18,8,18,6,16,19,10,10,21,12,18,15,13,8,

%U 18,15,19,15,13,7,24,7,13,19,16,12,18,8,17,15,20,9,24,9,13,22,17,13,22

%N Number of prime factors of 9^n - 1 (counted with multiplicity).

%H Max Alekseyev, <a href="/A057952/b057952.txt">Table of n, a(n) for n = 1..690</a> (first 330 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 A085034. - _T. D. Noe_, Jun 19 2003

%F a(n) = A001222(A024101(n)) = A057958(2*n). - _Amiram Eldar_, Feb 02 2020

%F a(n) = A057941(n) + A057958(n). - _Max Alekseyev_, Jan 07 2024

%t PrimeOmega[Table[9^n - 1, {n, 1, 30}]] (* _Amiram Eldar_, Feb 02 2020 *)

%Y bigomega(b^n-1): A046051 (b=2), A057958 (b=3), A057957 (b=4), A057956 (b=5), A057955 (b=6), A057954 (b=7), A057953 (b=8), this sequence (b=9), A057951 (b=10), A366682 (b=11), A366708 (b=12).

%Y Cf. A001222, A002591, A024101, A074477, A085034, A133801, A274909, A366660, A366661, A366662.

%K nonn

%O 1,1

%A _Patrick De Geest_, Nov 15 2000