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 A061883 #9 Feb 12 2016 17:06:27
%S A061883 1,1,1,3,6,10,21,36,78,153,300,595,1176,2346,4656,9316,18528,37128,
%T A061883 74305,148240,296835,593505,1186570,2372931,4744740,9489546,18975880,
%U A061883 37953828,75909681,151806600,303626403,607243825,1214480970,2428940451
%N A061883 Largest triangular number less than or equal to sum of previous terms with a(0)=1.
%C A061883 a(5)=10 since 1+1+1+3+6=12 and 10 is the largest triangular number less than or equal to this.
%H A061883 Harvey P. Dale, <a href="/A061883/b061883.txt">Table of n, a(n) for n = 0..1000</a>
%F A061883 a(n) = A060985(n+1)-A060985(n) = A057944(A060985(n)) = A000217(A003056(A060985(n)))
%t A061883 ltn[n_]:=Module[{c=Floor[(Sqrt[8*n+1]-1)/2]},(c(c+1))/2]; nxt[{t_, a_}] := Module[ {m = ltn[t]}, {t + m, m}]; Transpose[NestList[nxt,{1,1},40]] [[2]] (* _Harvey P. Dale_, Feb 12 2016 *)
%o A061883 (Haskell)
%o A061883 a061883 n = a061883_list !! n
%o A061883 a061883_list = 1 : zipWith (-) (tail a060985_list) a060985_list
%o A061883 -- _Reinhard Zumkeller_, Feb 03 2012
%K A061883 nonn
%O A061883 0,4
%A A061883 _Henry Bottomley_, May 12 2001