A023509 - OEIS

%I #13 Feb 06 2019 07:55:52

%S 3,2,3,2,3,7,3,5,3,5,2,19,7,11,3,3,5,31,17,3,37,5,7,5,7,17,13,3,11,19,

%T 2,11,23,7,5,19,79,41,7,29,5,13,3,97,11,5,53,7,19,23,13,5,11,7,43,11,

%U 5,17,139,47,71,7,11,13,157,53,83,13,29,7,59,5,23,17,19,3,13

%N Greatest prime divisor of prime(n) + 1.

%H T. D. Noe, <a href="/A023509/b023509.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A006530(A008864(n)). - _R. J. Mathar_, Feb 06 2019

%t Table[FactorInteger[Prime[n] + 1][[-1, 1]], {n, 100}]

%o (PARI) A023509(n) = {local(f);f=factor(prime(n)+1);f[matsize(f)[1],1]} \\ _Michael B. Porter_, Feb 02 2010

%K nonn

%O 1,1

%A _Clark Kimberling_