%I #9 Feb 12 2016 17:06:27

%S 1,1,1,3,6,10,21,36,78,153,300,595,1176,2346,4656,9316,18528,37128,

%T 74305,148240,296835,593505,1186570,2372931,4744740,9489546,18975880,

%U 37953828,75909681,151806600,303626403,607243825,1214480970,2428940451

%N Largest triangular number less than or equal to sum of previous terms with a(0)=1.

%C a(5)=10 since 1+1+1+3+6=12 and 10 is the largest triangular number less than or equal to this.

%H Harvey P. Dale, <a href="/A061883/b061883.txt">Table of n, a(n) for n = 0..1000</a>

%F a(n) = A060985(n+1)-A060985(n) = A057944(A060985(n)) = A000217(A003056(A060985(n)))

%t 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 (Haskell)

%o a061883 n = a061883_list !! n

%o a061883_list = 1 : zipWith (-) (tail a060985_list) a060985_list

%o -- _Reinhard Zumkeller_, Feb 03 2012

%K nonn

%O 0,4

%A _Henry Bottomley_, May 12 2001