%I A064840
%S A064840 1,6,8,21,12,48,16,60,39,72,24,168,28,96,96,155,36,234,40,252,128,144,
%T A064840 48,480,93,168,160,336,60,576,64,378,192,216,192,819,76,240,224,720,84,
%U A064840 768,88,504,468,288,96,1240,171,558,288,588,108,960,288,960,320,360
%N A064840 tau(n)*sigma(n).
%H A064840 Harry J. Smith, <a href="b064840.txt">Table of n, a(n) for n=1,...,1000</
               a>
%F A064840 Multiplicative with a(p^e) = (p^(e+1)-1)*(e+1)/(p-1). a(n) = 1/2*Sum_{i|n, 
               j|n} (i+j).
%e A064840 (MAGMA) [ NumberOfDivisors(n)*SumOfDivisors(n) : n in [1..40]];
%p A064840 with(numtheory): seq(sigma(n)*tau(n), n=1..58) ; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jun 04 2008
%o A064840 (PARI) { for (n=1, 1000, a=numdiv(n)*sigma(n); write("b064840.txt", n, 
               " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 
               28 2009]
%Y A064840 Cf. A000005, A000203, A007503.
%Y A064840 Sequence in context: A159469 A096524 A083595 this_sequence A084962 A024306 
               A024868
%Y A064840 Adjacent sequences: A064837 A064838 A064839 this_sequence A064841 A064842 
               A064843
%K A064840 mult,nonn
%O A064840 1,2
%A A064840 Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 25 2001