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A309941 Number of prime factors of n^n - 1, counted with multiplicity.

%I A309941 #19 Jul 04 2024 03:36:51
%S A309941 1,2,3,4,4,4,7,8,6,4,8,6,5,7,7,7,10,4,11,10,8,6,13,13,11,9,13,10,15,4,
%T A309941 13,12,13,10,18,11,8,10,16,9,16,6,15,18,9,5,19,20,14,15,17,8,16,12,18,
%U A309941 10,10,5,26,8,10,14,20,19,17,9,17,12,19,7,29,15,8,11,20,13,21,8
%N A309941 Number of prime factors of n^n - 1, counted with multiplicity.
%H A309941 Amiram Eldar, <a href="/A309941/b309941.txt">Table of n, a(n) for n = 2..138</a> (terms 2..126 from Chai Wah Wu)
%H A309941 factordb, <a href="http://factordb.com/index.php?query=n%5En-1&amp;use=n&amp;perpage=20&amp;format=1&amp;sent=1&amp;PR=1&amp;PRP=1&amp;C=1&amp;CF=1&amp;U=1&amp;FF=1&amp;VP=1&amp;EV=1&amp;OD=1&amp;VC=1&amp;n=80">Factors of n^n-1</a>.
%e A309941 a(3) = 2: 3^3 - 1 = 26 = 2 * 13.
%e A309941 a(5) = 4: 5^5 - 1 = 3124 = 2^2 * 11 * 71.
%t A309941 a[n_] := PrimeOmega[n^n - 1]; Array[a, 45, 2] (* _Amiram Eldar_, Jul 04 2024 *)
%o A309941 (PARI) for(k=2, 50, print1(bigomega(k^k-1),", "))
%Y A309941 Cf. A006486, A048861, A085723, A116895, A125135, A334167, A344870.
%K A309941 nonn,hard
%O A309941 2,2
%A A309941 _Hugo Pfoertner_, Aug 24 2019