OFFSET
1,1
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..500
EXAMPLE
81 = 45 + 36 = 66 + 15 = 78 + 3.
MATHEMATICA
Take[Transpose[Select[Split[Sort[Total/@(Union[Sort/@Tuples[Accumulate[ Range[300]], {2}]])]], Length[#]==3&]][[1]], 60] (* Harvey P. Dale, Jun 04 2011 *)
PROG
(PARI) Tri(n)= { n*(n + 1)/2 } { n=0; for (m=1, 10^9, k=0; i=1; until (t>=m\2 || k>3, t=Tri(i); j=i; i++; until (s>=m || k>3, s=t + Tri(j); j++; if (s==m, k++))); if (k==3, write("b064828.txt", n++, " ", m); if (n==1000, return)) ) } [Harry J. Smith, Sep 27 2009]
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Ayres (jonathan.ayres(AT)btinternet.com), Oct 23 2001
STATUS
approved