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A046053 Total number of prime factors of the repunit R(n) = (10^n-1)/9.

%I A046053 #27 Feb 16 2025 08:32:38
%S A046053 0,1,2,2,2,5,2,4,4,4,2,7,3,4,6,6,2,9,1,7,7,7,1,10,5,6,7,8,5,13,3,11,6,
%T A046053 6,7,12,3,3,6,11,4,15,4,11,10,6,2,13,4,10,8,9,4,14,8,12,6,8,2,20,7,5,
%U A046053 14,15,7,15,3,10,6,12,2,18,3,7,12,6,8,16,6,15,13,7,3,22,7,8,10,15,5
%N A046053 Total number of prime factors of the repunit R(n) = (10^n-1)/9.
%H A046053 Max Alekseyev, <a href="/A046053/b046053.txt">Table of n, a(n) for n = 1..352</a> (first 322 terms from Ray Chandler)
%H A046053 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Repunit.html">Repunit.</a>
%F A046053 a(n) = A001222(A002275(n)). - _Ray Chandler_, Apr 22 2017
%F A046053 a(n) = A057951(n) - 2. - _Ray Chandler_, Apr 24 2017
%e A046053 R(6) = 111111 = (3) (7) (11) (13) (37), so a(6) = 5.
%t A046053 Table[PrimeOmega[(10^n - 1)/9], {n, 60}] (* _Michael De Vlieger_, Apr 29 2015 *)
%o A046053 (PARI) a(n)=bigomega(10^n\9) \\ _Charles R Greathouse IV_, Apr 29 2015
%Y A046053 Cf. A001222, A002275, A057951. For the number of distinct prime factors see A095370.
%K A046053 nonn
%O A046053 1,3
%A A046053 _Eric W. Weisstein_