cp's OEIS Frontend

A054576 Largest proper factor of the largest proper factor of n.

%I A054576 #18 Dec 26 2022 13:44:57
%S A054576 1,1,1,1,1,1,1,2,1,1,1,3,1,1,1,4,1,3,1,5,1,1,1,6,1,1,3,7,1,5,1,8,1,1,
%T A054576 1,9,1,1,1,10,1,7,1,11,5,1,1,12,1,5,1,13,1,9,1,14,1,1,1,15,1,1,7,16,1,
%U A054576 11,1,17,1,7,1,18,1,1,5,19,1,13,1,20,9,1,1,21,1,1,1,22,1,15,1,23,1,1,1,24
%N A054576 Largest proper factor of the largest proper factor of n.
%C A054576 Here a "proper factor of n" means 1 if n = 1, and otherwise any d that divides n with 1 <= d < n. - _N. J. A. Sloane_, Dec 26 2022
%H A054576 Reinhard Zumkeller, <a href="/A054576/b054576.txt">Table of n, a(n) for n = 1..10000</a>
%F A054576 a(n) = A053598(A053598(n))
%F A054576 a(n) = A032742(A032742(n)); A117357(n) = A020639(a(n)); A117358(n) = A032742(a(n)) = a(n) / A117357(n); a(A037143(n)) = 1, a(A033942(n)) > 1. - _Reinhard Zumkeller_, Mar 10 2006
%e A054576 The largest proper factor of 8 is 4, the largest proper factor of 4 is 2, so a(8) = 2. - _N. J. A. Sloane_, Dec 26 2022
%o A054576 (Haskell) a054576 = a032742 . a032742  -- _Reinhard Zumkeller_, Jan 31 2015
%o A054576 (PARI) A054576(n)=A032742(A032742(n)) \\ _M. F. Hasler_, Apr 03 2017
%Y A054576 Cf. A053598.
%Y A054576 Cf. A020639, A032742, A033942, A037143, A117357, A117358.
%K A054576 easy,nonn
%O A054576 1,8
%A A054576 _Henry Bottomley_, Apr 11 2000
%E A054576 Deleted an incorrect comment and link. - _N. J. A. Sloane_, Dec 26 2022