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 A074285 #26 Aug 18 2021 07:57:53
%S A074285 1,4,12,18,24,32,56,91,78,72,144,168,112,192,360,270,234,260,360,576,
%T A074285 384,288,672,868,434,560,960,720,720,768,992,1488,864,864,1872,1482,
%U A074285 760,1120,2352,1764,1344,1408,1584,2808,1872,1152,2880,3420,1767,2232
%N A074285 Sum of the divisors of n-th triangular number.
%C A074285 By definition a(n) is also the sum of the divisors of n-th generalized hexagonal number. - _Omar E. Pol_, Nov 24 2015
%H A074285 T. D. Noe, <a href="/A074285/b074285.txt">Table of n, a(n) for n = 1..1000</a>
%F A074285 a(n) = A000203(A000217(n)). - _Omar E. Pol_, Nov 24 2015
%F A074285 Sum_{k=1..n} a(k) ~ n^3/3. - _Vaclav Kotesovec_, Aug 18 2021
%e A074285 a(4)=18 because the sum of divisors of the 4th triangular number (i.e., 10) is 1 + 2 + 5 + 10 = 18.
%t A074285 Table[DivisorSigma[1, n*(n + 1)/2], {n, 1, 100}] (* _Vaclav Kotesovec_, Aug 18 2021 *)
%o A074285 (PARI) a(n) = sigma(n*(n+1)/2); \\ _Altug Alkan_, Nov 24 2015
%Y A074285 Cf. A000203, A000217, A330322.
%K A074285 nonn
%O A074285 1,2
%A A074285 _Shyam Sunder Gupta_, Sep 21 2002