A104360 - OEIS

%I #23 Oct 03 2022 17:04:41

%S 0,1,1,1,1,1,2,1,1,1,2,2,2,2,1,2,3,3,1,3,3,3,1,2,4,4,2,2,5,4,2,3,2,3,

%T 1,3,4,3,5,3,4,4,5,1,3,4,2,2,2,3,1,2,3,2,3,1,4,1,3,4,6,4,4,2,6,1,5,4,

%U 4,1,2,5,7,4,5,3,4,4,5,4,5,2,4,4,5,3,3,3,2,5,2,5,4,7,2,5,3,2,6,3,4,2,3,3,3,5,4,3,5,2

%N Number of distinct prime factors of A104357(n) = A104350(n) - 1.

%H Max Alekseyev, <a href="/A104360/b104360.txt">Table of n, a(n) for n = 2..145</a>

%H Reinhard Zumkeller, <a href="/A104350/a104350.txt">Products of largest prime factors of numbers <= n</a>

%F a(n) = A001221(A104357(n)).

%t A104350[n_] := Product[FactorInteger[k][[-1, 1]], {k, 1, n}]; PrimeNu[Table[A104350[n] - 1, {n, 2,50}]] (* _G. C. Greubel_, May 10 2017 *)

%Y Cf. A001221, A054989, A066877, A104350, A104357, A104358, A104359, A104361, A104362, A104363, A104364, A104368.

%K nonn

%O 2,7

%A _Reinhard Zumkeller_, Mar 06 2005

%E a(51)-a(74) from _Amiram Eldar_, Feb 12 2020

%E More terms from _Jinyuan Wang_, Apr 02 2020

%E Terms a(90) onward from _Max Alekseyev_, Oct 03 2022