A060476 - OEIS

%I #20 Oct 18 2020 03:07:51

%S 1,8,24,27,32,40,54,56,72,88,96,104,108,120,125,128,135,136,152,160,

%T 168,184,189,200,216,224,232,243,248,250,256,264,270,280,288,296,297,

%U 312,328,343,344,351,352,360,375,376,378,384,392,408,416,424,440,456,459,472,480

%N Let n = 2^e_2 * 3^e_3 * 5^e_5 * ... be the prime factorization of n; sequence gives n such that 1 + max{e_2, e_3, ...} is nonprime.

%C The old entry with this sequence number was a duplicate of A005171.

%C The asymptotic density of this sequence is Sum_{c composite} (1/zeta(c) - 1/zeta(c-1)) = 0.1182437806... - _Amiram Eldar_, Oct 18 2020

%H Charles R Greathouse IV, <a href="/A060476/b060476.txt">Table of n, a(n) for n = 1..10000</a>

%F From _Reinhard Zumkeller_, Nov 30 2015: (Start)

%F A010051(A051903(a(n)+1)) = 1.

%F a(A055229(n)) > 1 for n > 1. (End)

%t Join[{1}, Select[Range[500], !PrimeQ[1+Max[FactorInteger[#][[All, 2]]]]&]] (* _Jean-François Alcover_, Aug 02 2018 *)

%o (PARI) isA060476(n) = if(n<2,1,!isprime(vecmax(factor(n)[,2])+1))

%o (Haskell)

%o a060476 n = a060476_list !! (n-1)

%o a060476_list = filter ((== 0) . a010051' . (+ 1) . a051903) [1..]

%o -- _Reinhard Zumkeller_, Nov 30 2015

%Y Cf. A096432, A074661.

%Y Cf. A010051, A051903, A055229.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Sep 18 2008