%I #14 Dec 23 2024 09:54:39
%S 1,7,10,27,16,64,22,83,55,102,34,236,40,140,140,227,52,343,58,372,192,
%T 216,70,708,141,254,244,510,88,866,94,579,296,330,296,1241,112,368,
%U 348,1104,124,1184,130,786,728,444,142,1908,267,877,452,924,160,1504,456
%N a(n) = Sum_{i|n, j|n} max(i,j).
%H Harry J. Smith, <a href="/A064948/b064948.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = Sum_{i=1..tau(n)} (2*i-1)*d_i, where {d_i}, i=1..tau(n), is the increasing sequence of the divisors of n.
%F a(n) = 2*A064944(n) - A000203(n). - _Amiram Eldar_, Dec 23 2024
%e a(6) = dot_product(1,3,5,7)*(1,2,3,6) = 1*1 + 3*2 + 5*3 + 7*6 = 64.
%p with(numtheory): seq(add((2*i-1)*sort(convert(divisors(n),'list'))[i],i=1..tau(n)), n=1..200);
%o (PARI) { for (n=1, 1000, d=divisors(n); a=sum(i=1, length(d), (2*i - 1)*d[i]); write("b064948.txt", n, " ", a) ) } \\ _Harry J. Smith_, Oct 01 2009
%Y Cf. A000005, A000203, A064944.
%K nonn
%O 1,2
%A _Vladeta Jovovic_, Oct 28 2001