%I A060794
%S A060794 1,2,1,4,1,6,2,2,3,10,1,12,5,2,2,16,3,18,1,4,9,22,2,4,11,6,3,28,1,30,4,
%T A060794 8,15,2,2,36,17,10,3,40,1,42,7,4,21,46,2,6,5,14,9,52,3,6,1,16,27,58,4,
%U A060794 60,29,2,4,8,5,66,13,20,3,70,1,72,35,10,15,4,7,78,2,6,39,82,5,12,41,26
%N A060794 Difference between upper and lower central divisors of n.
%H A060794 Harry J. Smith, <a href="b060794.txt">Table of n, a(n) for n=2,...,1000</
               a>
%e A060794 Difference between upper and lower central divisors may be small or relatively 
               large. So neither A060775 nor A033677 are always good central divisors 
               as to their magnitude. n=182,D={1,2,7,13,14,26,91,182}; central divisors={13,
               14}, difference=1. n=254, D={1,2,127,254}, central divisors={2,127}, 
               a(254)=125. n=p, D={1,p}. Here the central divisors are also marginal 
               ones: a(p)=p-1.
%t A060794 a(n)=Part[Divisors[n], 1+cd[n]]-Part[Divisors[n], cd[n]], where cd[x_] 
               := cd[x_] := Floor[DivisorSigma[0, x]/2]
%o A060794 (PARI) { for (n=2, 1000, d=divisors(n); write("b060794.txt", n, " ", 
               d[1 + length(d)\2] - d[length(d)\2]); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Jul 12 2009]
%Y A060794 a(n)=A033677(n)-A060775(n).
%Y A060794 Cf. A060775-A060777, A033677, A000196.
%Y A060794 Sequence in context: A147064 A147228 A074643 this_sequence A074919 A138009 
               A131755
%Y A060794 Adjacent sequences: A060791 A060792 A060793 this_sequence A060795 A060796 
               A060797
%K A060794 nonn
%O A060794 2,2
%A A060794 Labos E. (labos(AT)ana.sote.hu), Apr 27 2001