%I #10 Aug 17 2019 01:15:31

%S 0,3,5,7,3,11,13,8,17,19,10,23,5,3,29,31,14,12,37,16,41,43,8,47,7,20,

%T 53,16,22,59,61,10,18,67,26,71,73,8,18,79,3,83,22,32,89,20,34,24,97,

%U 14,101,103,15,107,109,40,113,28,16,24,11,44,5,127,46,131,26,8,137,139,50,24

%N Bisection of A008472.

%C The sum of the distinct primes dividing 2n-1. - _Emeric Deutsch_, Mar 11 2005

%e a(23)=8 because 45=3^2*5 and 3+5=8.

%p with(numtheory): a:=proc(n) local b: b:=convert(factorset(2*n-1),list): add(b[j],j=1..nops(b)) end: seq(a(n),n=1..80); # _Emeric Deutsch_, Mar 11 2005

%t Join[{0},Total[Transpose[FactorInteger[#]][[1]]]&/@(2*Range[2,80]-1)] (* _Harvey P. Dale_, Aug 05 2015 *)

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_, Nov 20 2004

%E More terms from _Emeric Deutsch_, Mar 11 2005