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 A049991 #42 Sep 30 2019 02:00:49
%S A049991 0,1,3,6,9,15,19,25,33,41,47,60,67,77,92,104,113,132,142,158,178,193,
%T A049991 205,231,247,264,289,310,325,359,375,397,427,449,473,513,532,556,591,
%U A049991 623,644,689,711,741,788,817,841,892,920,957,1003,1038,1065,1121,1157,1197,1248,1284,1314,1384,1415
%N A049991 a(n) is the number of arithmetic progressions of 2 or more positive integers, nondecreasing with sum <= n.
%H A049991 Sadek Bouroubi and Nesrine Benyahia Tani, <a href="http://ftp.math.uni-rostock.de/pub/romako/heft64/bou64.pdf">Integer partitions into arithmetic progressions</a>, Rostok. Math. Kolloq. 64 (2009), 11-16.
%H A049991 Sadek Bouroubi and Nesrine Benyahia Tani, <a href="http://www.emis.de/journals/INTEGERS/papers/j7/j7.Abstract.html">Integer partitions into arithmetic progressions with an odd common difference</a>, Integers 9(1) (2009), 77-81.
%H A049991 Graeme McRae, <a href="https://web.archive.org/web/20081122034835/http://2000clicks.com/MathHelp/BasicSequenceA049982.htm">Counting arithmetic sequences whose sum is n</a>.
%H A049991 Graeme McRae, <a href="/A049988/a049988.pdf">Counting arithmetic sequences whose sum is n</a> [Cached copy]
%H A049991 Augustine O. Munagi, <a href="https://www.emis.de/journals/INTEGERS/papers/k7/k7.Abstract.html">Combinatorics of integer partitions in arithmetic progression</a>, Integers 10(1) (2010), 73-82.
%H A049991 Augustine O. Munagi and Temba Shonhiwa, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL11/Shonhiwa/shonhiwa13.html">On the partitions of a number into arithmetic progressions</a>, Journal of Integer Sequences 11 (2008), Article 08.5.4.
%H A049991 A. N. Pacheco Pulido, <a href="http://www.bdigital.unal.edu.co/7753/">Extensiones lineales de un poset y composiciones de números multipartitos</a>, Maestría thesis, Universidad Nacional de Colombia, 2012.
%H A049991 Wikipedia, <a href="https://en.wikipedia.org/wiki/Arithmetic_progression">Arithmetic progression</a>.
%F A049991 From _Petros Hadjicostas_, Sep 29 2019: (Start)
%F A049991 a(n) = Sum_{k = 1..n} A049990(k).
%F A049991 G.f.: (g.f. of A049990)/(1-x). (End)
%Y A049991 Cf. A014405, A014406, A049980, A049981, A049982, A049983, A049987, A049988, A049989, A049990, A049991, A111333, A127938.
%K A049991 nonn
%O A049991 1,3
%A A049991 _Clark Kimberling_
%E A049991 More terms from _Petros Hadjicostas_, Sep 29 2019