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 A355875 #21 Aug 23 2022 09:58:53
%S A355875 0,1,0,2,0,5,0,4,0,5,0,13,0,7,6,8,0,15,0,14,0,11,0,26,0,13,0,26,0,42,
%T A355875 0,16,0,17,10,39,0,19,0,43,0,41,0,22,38,23,0,52,0,25,0,26,0,45,0,59,0,
%U A355875 29,0,111,0,31,14,32,0,85,0,34,0,76,0,86,0,37,30,38
%N A355875 For n >= 1, k >= 1; a(n) = Sum_{k=1..n} f(n,k). f(n,k) = n*k/(n + k) if n*k divides (n+k), 0 otherwise.
%C A355875 a(n) = n/2 for n in A125499.
%C A355875 a(n) = 0 for n in A244579.
%e A355875 n = 6; a(6) = Sum_{k=1..6} f(6,k) = 0 + 0 + 2 + 0 + 0 + 3 = 5.
%t A355875 a[n_] := Sum[If[Divisible[n*k, n + k], n*k/(n + k), 0], {k, 1, n}]; Array[a, 100] (* _Amiram Eldar_, Jul 21 2022 *)
%Y A355875 Cf. A005279, A125499, A244579.
%K A355875 nonn
%O A355875 1,4
%A A355875 _Ctibor O. Zizka_, Jul 19 2022