A344869 - OEIS

%I #39 Sep 27 2024 07:50:10

%S 1,1,1,2,1,3,3,3,3,4,3,6,4,5,5,6,2,3,7,5,3,6,4,8,6,7,5,11,6,7,10,7,4,

%T 11,6,13,5,7,7,8,9,6,10,8,8,14,8,10,6,7,10,11,5,8,14,11,7,13,13,9,12,

%U 8,7,18,4,12,8,7,7,16,9,8,12,4,8,24,7,9,14,7,5,12,6,12,8,13,10,12,10,6,23,15,6,9,11,16,3,8,17,23,7

%N Number of distinct prime factors of n^n+1.

%H Amiram Eldar, <a href="/A344869/b344869.txt">Table of n, a(n) for n = 0..148</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SierpinskiNumberoftheFirstKind.html">Sierpinski Number of the First Kind</a>.

%F a(n) = A001221(A014566(n)).

%t a[0] = 1; a[n_] := PrimeNu[n^n + 1]; Array[a, 45, 0] (* _Amiram Eldar_, May 31 2021 *)

%o (PARI) a(n) = omega(n^n+1);

%o (Magma) [#PrimeDivisors(n^n+1): n in [0..100]];

%Y Cf. A001221, A014566, A085723, A128428, A344859, A344870.

%K nonn

%O 0,4

%A _Seiichi Manyama_, May 31 2021

%E a(67)-a(79) from _Jon E. Schoenfield_, May 31 2021

%E a(80)-a(100) from _Seiichi Manyama_, May 31 2021