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 A346879 #20 Aug 20 2021 00:23:14 %S A346879 0,0,0,0,3,0,0,8,0,0,10,0,5,12,0,0,14,12,0,16,0,0,32,0,7,20,0,16,22,0, %T A346879 0,40,18,0,26,0,0,48,18,0,39,0,22,32,0,20,34,24,0,56,0,0,86,0,0,40,0, %U A346879 28,64,24,11,44,30,0,46,0,26,104,0,0,50,24,34,80,0,0,80,36 %N A346879 Sum of the divisors, except the smallest and the largest, of the n-th odd number. %C A346879 a(n) has a symmetric representation. %F A346879 a(n) = A048050(2*n-1). %e A346879 For n = 5 the 5th odd number is 9 and the divisors of 9 are [1, 3, 9] and the sum of the divisors of 9 except the smaller and the largest is 3, so a(5) = 3. %e A346879 For n = 6 the 6th odd number is 11 and the divisors of 11 are [1, 11] and the sum of the divisors of 11 except the smaller and the largest is 0, so a(6) = 0. %t A346879 a[1] = 0; a[n_] := DivisorSigma[1, 2*n - 1] - 2*n; Array[a, 100] (* _Amiram Eldar_, Aug 19 2021 *) %o A346879 (Python) %o A346879 from sympy import divisors %o A346879 def a(n): return sum(divisors(2*n-1)[1:-1]) %o A346879 print([a(n) for n in range(1, 79)]) # _Michael S. Branicky_, Aug 19 2021 %Y A346879 Bisection of A048050. %Y A346879 Partial sums give A346869. %Y A346879 Cf. A000203, A005408, A008438, A237593, A245092, A244049, A326123, A346880. %K A346879 nonn,easy %O A346879 1,5 %A A346879 _Omar E. Pol_, Aug 18 2021