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 A165929 #11 Oct 02 2023 20:17:29
%S A165929 1,1,3,6,12,24,48,120,264,480,1104,2064,4128,10752,19320,38328,91992,
%T A165929 170016,369600,745560,1854720,3845760,7765296,14990520,29910120,
%U A165929 59856720,119710416,298755600,667297320,1446528360,4011171840
%N A165929 a(1) = 1; for n > 1, a(n) = sigma(sum of the previous terms) where sigma(k) = sum of the divisors of k.
%C A165929 a(1) = 1; for n > 1, a(n) = sigma(Sum_{i=1..n-1} a(i)) = A000203(Sum_{i=1..n-1} a(i)).
%C A165929 a(n) = inverse of partial sums of A081973(n), i.e., a(1) = A081973(1); for n > 1, a(n) = A081973(n) - A081973(n-1), i.e., first differences of A081973.
%e A165929 a(4) = sigma(a(1) + a(2) + a(3)) = sigma(1+1+3) = sigma(5) = 6.
%t A165929 Module[{lst={1}},Do[AppendTo[lst,DivisorSigma[1,Total[lst]]],{40}]; lst] (* _Harvey P. Dale_, Sep 29 2012 *)
%o A165929 (PARI) print1(1);s=1;for(i=1,100,k=sigma(s);print1(","k);s+=k)
%K A165929 nonn
%O A165929 1,3
%A A165929 _Jaroslav Krizek_, Sep 30 2009
%E A165929 Extension and program from _Charles R Greathouse IV_, Oct 12 2009