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 A355750 #10 Jul 18 2022 19:41:40
%S A355750 1,4,8,11,14,22,20,26,33,36,32,52,38,50,64,57,50,82,56,82,88,78,68,
%T A355750 114,87,92,112,112,86,156,92,120,136,120,136,183,110,134,160,176,122,
%U A355750 212,128,172,222,162,140,240,165,208,208,202,158,268,208,238,232,204,176,344,182
%N A355750 Sum of the divisors of 2n minus the number of divisors of 2n.
%C A355750 Consider the partitions of 2n into 2 parts (s,t), where s <= t. a(n) gives the sum of all the quotients t/s such that t/s is an integer. (See example.)
%F A355750 a(n) = sigma(2n) - tau(2n).
%F A355750 a(n) = Sum_{d|2n} (2n-d)/d.
%F A355750 a(n) = A065608(2n) = A000203(2n) - A000005(2n).
%F A355750 a(n) = A062731(n) - A099777(n).
%F A355750 a(n) = Sum_{k=1..n} m*c(m), where m=(2n-k)/k and c(m)=1-ceiling(m)+floor(m).
%e A355750 a(7) = 20; the partitions of 2*7 = 14 into two parts (s,t) where s <= t are: (1,13), (2,12), (3,11), (4,10), (5,9), (6,8), and (7,7). The sum of the quotients t/s such that each t/s is an integer is then: 13/1 + 12/2 + 7/7 = 13 + 6 + 1 = 20.
%t A355750 Table[DivisorSigma[1, 2 n] - DivisorSigma[0, 2 n], {n, 80}]
%o A355750 (PARI) a(n) = my(f=factor(2*n)); sigma(f) - numdiv(f); \\ _Michel Marcus_, Jul 16 2022
%Y A355750 Cf. A000005 (tau), A000203 (sigma), A062731, A099777.
%Y A355750 Bisection of A065608.
%K A355750 nonn,easy
%O A355750 1,2
%A A355750 _Wesley Ivan Hurt_, Jul 15 2022