%I #17 Jan 09 2025 13:20:26

%S 3,5,7,3,11,13,4,17,19,5,23,5,3,29,31,7,6,37,8,41,43,4,47,7,10,53,8,

%T 11,59,61,5,9,67,13,71,73,4,9,79,3,83,11,16,89,10,17,12,97,7,101,103,

%U 5,107,109,20,113,14,8,12,11,22,5,127,23,131,13,4,137,139,25,12,17,5,149,151

%N a(n) = (A020639(2n+1) + A006530(2n+1))/2, arithmetic mean of max and min prime factor applied to odd numbers (i.e., when this mean is an integer).

%H Michael De Vlieger, <a href="/A088836/b088836.txt">Table of n, a(n) for n = 1..10000</a>

%e If 2n+1 is prime then a(2n+1) = 2n + 1.

%t Table[(FactorInteger[2 n + 1][[1, 1]] + FactorInteger[2 n + 1][[-1, 1]])/2, {n, 75}] (* _Michael De Vlieger_, Mar 28 2015 *)

%Y Cf. A020639, A006530.

%K nonn

%O 1,1

%A _Labos Elemer_, Oct 31 2003