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 A343781 #12 May 19 2021 11:41:11
%S A343781 0,1,3,9,17,55,111,457,943,4962,11148,69526,159402,1161340,2765874,
%T A343781 22829766,55192956,510771772,1257880780,12870681814,32042113008,
%U A343781 359566186586,904795505226,11043196798176,28002785395660,369463867367567,943392140873807,13378621275148931
%N A343781 a(n) = Sum_{k=1..floor(n/2)} sigma_k(n-k), where sigma_k(n) is the sum of the k-th powers of the divisors of n.
%e A343781 a(5) = 17; a(5) = Sum_{i=1..2} sigma_k(5-k) = sigma_1(4) + sigma_2(3) = (1+2+4) + (1^2+3^2) = 7 + 10 = 17.
%t A343781 Table[Sum[DivisorSigma[i, n - i], {i, Floor[n/2]}], {n, 30}]
%o A343781 (PARI) a(n) = sum(k=1, n\2, sigma(n-k, k)); \\ _Michel Marcus_, Apr 29 2021
%Y A343781 Cf. A245466.
%K A343781 nonn
%O A343781 1,3
%A A343781 _Wesley Ivan Hurt_, Apr 29 2021