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 A075349 #10 Jul 30 2017 00:05:36
%S A075349 1,2,4,6,9,12,15,19,23,27,31,36,41,46,51,56,62,68,74,80,86,92,99,106,
%T A075349 113,120,127,134,141,149,157,165,173,181,189,197,205,214,223,232,241,
%U A075349 250,259,268,277,286,296,306,316,326,336,346,356,366,376,386,397,408
%N A075349 a(1) = 1; first differences follow the pattern 1,2,2,3,3,3,4,4,4,4,5,5,5,5,5,..., i.e., the next n differences are n.
%H A075349 Harvey P. Dale, <a href="/A075349/b075349.txt">Table of n, a(n) for n = 1..10000</a>
%F A075349 a(n) = A060432(n-1) + 1. - _David Wasserman_, Jan 16 2005
%t A075349 Accumulate[Join[{1},Flatten[Table[Table[n,{n}],{n,12}]]]] (* _Harvey P. Dale_, Aug 26 2013 *)
%K A075349 nonn
%O A075349 1,2
%A A075349 _Amarnath Murthy_, Sep 19 2002
%E A075349 More terms from _David Wasserman_, Jan 16 2005