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 A239876 #11 Jan 12 2025 11:11:04
%S A239876 0,0,2,5,9,12,18,23,28,35,45,47,59,70,76,85,101,107,125,133,143,162,
%T A239876 184,184,203,226,240,254,282,285,315,332,350,381,403,438,474,509,531,
%U A239876 541,581,590,632,658,670,713,759,803,844,876,906,938,990,1005,1043,1063
%N A239876 Partial sums of A229110, where A229110(n) = antisigma(n) mod n = A024816(n) mod n.
%C A239876 Antisigma(n) = A024816(n) = sum of non-divisors of n.
%C A239876 See A239877 - values of n for which a(n)/n is an integer.
%H A239876 Jaroslav Krizek, <a href="/A239876/b239876.txt">Table of n, a(n) for n = 1..1000</a>
%F A239876 a(n) = Sum_{k = 1...n} antisigma(k) mod k = Sum_{k = 1...n} A229110(k).
%F A239876 a(n) = a(n-1) for numbers n from A159907 if there are no odd multiply perfect numbers (A007691).
%t A239876 Accumulate[Table[Mod[Total[Complement[Range[n],Divisors[n]]],n],{n,60}]] (* _Harvey P. Dale_, Jul 05 2024 *)
%o A239876 (Magma)[&+[(k*(k+1)div 2 - SumOfDivisors (k)) mod k: k in [1..n]]: n in [1..1000]]
%Y A239876 Cf. A024816, A229110, A239877.
%K A239876 nonn
%O A239876 1,3
%A A239876 _Jaroslav Krizek_, Mar 29 2014