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 A294889 #11 Mar 14 2024 03:48:27
%S A294889 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,12,0,0,0,0,0,0,0,0,0,0,
%T A294889 0,30,0,0,0,20,0,0,0,0,0,0,0,36,0,0,0,0,0,18,0,0,0,0,0,62,0,0,0,0,0,0,
%U A294889 0,0,0,0,0,90,0,0,0,0,0,0,0,60,0,0,0,54,0,0,0,0,0,48,0,0,0,0,0,84,0,0,0,20,0,0,0,0,0
%N A294889 Sum of abundant proper divisors of n.
%C A294889 Sum of divisors of n smaller than n that are abundant numbers (in A005101).
%H A294889 Antti Karttunen, <a href="/A294889/b294889.txt">Table of n, a(n) for n = 1..20000</a>
%H A294889 <a href="/index/Su#sums_of_divisors">Index entries for sequences related to sums of divisors</a>.
%F A294889 a(n) = Sum_{d|n, d<n} A294937(d)*d.
%F A294889 a(n) = A187795(n) - (A294937(n)*n).
%F A294889 a(n) + A294888(n) = A001065(n).
%e A294889 The proper divisors of 60 are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30. Of these 12, 20 and 30 are in A005101, thus a(60) = 12+20+30 = 62.
%t A294889 a[n_] := DivisorSum[n, # &, # < n && DivisorSigma[1, #] > 2*# &]; Array[a, 100] (* _Amiram Eldar_, Mar 14 2024 *)
%o A294889 (PARI) A294889(n) = sumdiv(n, d, (d<n)*(sigma(d)>(2*d))*d);
%Y A294889 Cf. A001065, A005101, A187795, A294929, A294937, A294886, A294887, A294888.
%K A294889 nonn
%O A294889 1,24
%A A294889 _Antti Karttunen_, Nov 14 2017