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 A323643 #22 Apr 14 2019 06:16:13
%S A323643 0,0,0,5,0,7,0,9,10,11,0,21,0,15,16,27,0,30,0,33,22,23,0,50,26,27,28,
%T A323643 45,0,61,0,51,34,35,36,85,0,39,40,77,0,83,0,69,64,47,0,110,50,78,52,
%U A323643 81,0,105,56,105,58,59,0,152,0,63,88,119,66,127,0,105,70,127
%N A323643 a(n) is the sum of the noncentral divisors of n.
%C A323643 a(n) = 0 iff n is 1 or a prime (A008578).
%H A323643 Harvey P. Dale, <a href="/A323643/b323643.txt">Table of n, a(n) for n = 1..1000</a>
%F A323643 a(n) = A000203(n) - A207376(n).
%e A323643 For n = 12 the divisors of 12 are 1, 2, 3, 4, 6, 12. The central divisors of 12 are both 3 and 4, therefore the noncentral divisors are 1, 2, 6, 12, and the sum of them is 1 + 2 + 6 + 12 = 21, so a(12) = 21.
%e A323643 For n = 16 the divisors of 16 are 1, 2, 4, 8, 16. The central divisor of 16 is 4, therefore the noncentral divisors of 16 are 1, 2, 8, 16, and the sum of them is 1 + 2 + 8 + 16 = 27, so a(16) = 27.
%t A323643 sncd[n_]:=Module[{d=Divisors[n],len},len=Length[d];If[EvenQ[len],Total[ Drop[ d, {len/2,len/2+1}]],Total[Drop[d,{(len+1)/2}]]]]; Array[sncd,70] (* _Harvey P. Dale_, Apr 13 2019 *)
%Y A323643 Cf. A000203, A008578, A027750, A161840, A169695, A207375, A207376.
%K A323643 nonn,easy,look
%O A323643 1,4
%A A323643 _Omar E. Pol_, Feb 25 2019