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Sum of the lengths of the distinct rectangles with prime length and integer width such that L + W = n, W < L.
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%I #24 Dec 09 2023 22:56:58

%S 0,0,2,3,3,5,5,12,12,7,7,18,18,24,24,24,24,41,41,60,60,49,49,72,72,59,

%T 59,59,59,88,88,119,119,102,102,102,102,120,120,120,120,161,161,204,

%U 204,181,181,228,228,228,228,228,228,281,281,281,281,252,252,311

%N Sum of the lengths of the distinct rectangles with prime length and integer width such that L + W = n, W < L.

%C Sum of the largest parts of the partitions of n into two distinct parts with largest part prime.

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

%F a(n) = Sum_{i=1..floor((n-1)/2)} (n-i) * A010051(n-i).

%F a(n) = n*A294602(n) - A368058(n). - _Wesley Ivan Hurt_, Dec 09 2023

%e a(14) = 24; the rectangles are 1 X 13 and 3 X 11 (7 X 7 is not considered since W < L). The sum of the lengths is then 13 + 11 = 24.

%t Table[ Sum[(n - i)*(PrimePi[n - i] - PrimePi[n - i - 1]), {i, Floor[(n-1)/2]}], {n, 60}]

%o (PARI) a(n) = sum(i=1, (n-1)\2, (n-i)*isprime(n-i)); \\ _Michel Marcus_, Nov 08 2017

%Y Cf. A010051, A243485, A294602, A368058.

%K nonn,easy

%O 1,3

%A _Wesley Ivan Hurt_, Oct 31 2017