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Total area of all rectangles with dimensions s and t such that s | t, n = s + t and s < t.
3

%I #19 Sep 08 2022 08:46:21

%S 0,0,2,3,4,13,6,19,26,25,10,90,12,37,100,91,16,166,18,194,172,61,22,

%T 446,124,73,260,322,28,635,30,395,364,97,380,1041,36,109,484,990,40,

%U 1091,42,650,1144,133,46,1966,342,770,772,850,52,1651,788,1686,940

%N Total area of all rectangles with dimensions s and t such that s | t, n = s + t and s < t.

%H <a href="/index/Par#part">Index entries for sequences related to partitions</a>

%F a(n) = Sum_{i=1..floor((n-1)/2)} i * (n-i) * (floor((n-i)/i) - floor((n-i-1)/i)).

%t Table[Sum[i (n - i) (Floor[(n - i)/i] - Floor[(n - i - 1)/i]), {i, Floor[(n - 1)/2]}], {n, 80}]

%o (Magma) [0,0] cat [&+[k*(n-k)*(((n-k) div k)-((n-k-1) div k)): k in [1..(n-1) div 2]]: n in [3..80]]; // _Vincenzo Librandi_, Apr 23 2018

%Y Cf. A303384.

%K nonn,easy

%O 1,3

%A _Wesley Ivan Hurt_, Apr 22 2018

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