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A321165 Sum of distinct products i*j with 1 <= i, j <= n 2

%I

%S 1,7,25,61,136,244,440,680,1022,1472,2198,2882,4065,5241,6681,8265,

%T 10866,13116,16726,19786,23566,27922,34270,38902,45502,52600,60430,

%U 68326,80941,89671,105047,116855,130913,146519,163214,177002,203013,224673,247605,268005,303306

%N Sum of distinct products i*j with 1 <= i, j <= n

%H Seiichi Manyama, <a href="/A321165/b321165.txt">Table of n, a(n) for n = 1..1000</a>

%F a(p) = a(p - 1) + p ^ 2 * (p + 1) / 2 for prime p. - _David A. Corneth_, Jan 10 2019

%e a(2) = 1 + 2 + 4 = 7.

%e a(3) = 1 + 2 + 3 + 4 + 6 + 9 = 25.

%o (PARI) a(n) = vecsum(setbinop((x, y)->x*y, vector(n, i, i); )); \\ _Michel Marcus_, Jan 10 2019

%Y Column 2 of A321163.

%Y Cf. A027424.

%K nonn

%O 1,2

%A _Seiichi Manyama_, Jan 10 2019

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Last modified March 20 23:22 EDT 2019. Contains 321354 sequences. (Running on oeis4.)