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 A365540 #9 Sep 09 2023 11:24:22
%S A365540 0,1,5,12,24,39,61,86,118,155,199,246,304,365,433,508,592,679,777,878,
%T A365540 990,1109,1235,1364,1508,1657,1813,1976,2150,2327,2519,2714,2920,3133,
%U A365540 3353,3580,3824,4071,4325,4586,4862,5141,5435,5732,6040,6359,6685,7014,7362
%N A365540 Antidiagonal sums of A365539.
%F A365540 a(n) = Sum_{m=1..n} (Sum_{k=1..m} (2*A000005(k) - 1)).
%t A365540 A365539[n_,k_]:=SeriesCoefficient[(1+x^k)/((1-x)^2*(1-x^k)),{x,0,n}]; Table[Sum[A365539[n-k,k], {k,n}], {n,0,48}] (* or *)
%t A365540 Table[Sum[Sum[2 DivisorSigma[0,k]-1,{k,m}],{m,n}],{n,0,48}]
%Y A365540 Cf. A000005, A114003 (2nd differences), A365539.
%K A365540 nonn
%O A365540 0,3
%A A365540 _Stefano Spezia_, Sep 08 2023