This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A321165 #19 Jul 23 2025 15:59:59 %S A321165 1,7,25,61,136,244,440,680,1022,1472,2198,2882,4065,5241,6681,8265, %T A321165 10866,13116,16726,19786,23566,27922,34270,38902,45502,52600,60430, %U A321165 68326,80941,89671,105047,116855,130913,146519,163214,177002,203013,224673,247605,268005,303306 %N A321165 Sum of distinct products i*j with 1 <= i, j <= n. %H A321165 Seiichi Manyama, <a href="/A321165/b321165.txt">Table of n, a(n) for n = 1..1000</a> %F A321165 a(p) = a(p - 1) + p ^ 2 * (p + 1) / 2 for prime p. - _David A. Corneth_, Jan 10 2019 %e A321165 a(2) = 1 + 2 + 4 = 7. %e A321165 a(3) = 1 + 2 + 3 + 4 + 6 + 9 = 25. %o A321165 (PARI) a(n) = vecsum(setbinop((x, y)->x*y, vector(n, i, i); )); \\ _Michel Marcus_, Jan 10 2019 %Y A321165 Column 2 of A321163. %Y A321165 Cf. A027424. %K A321165 nonn %O A321165 1,2 %A A321165 _Seiichi Manyama_, Jan 10 2019