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%I #5 Dec 05 2013 19:55:14
%S 55,66,2415,3003,5050,5151,5995,8778,9045,113050,138075,171405,174345,
%T 177906,183921,198765,203203,216153,219453,234270,237705,239086,
%U 252405,255255,266815,267546,275653,279378,284635,293761,294528,306153,309291,329266,348195
%N Triangular numbers containing 2n digits in which the sum of the first n digits = that of the rest.
%H Harvey P. Dale, <a href="/A068898/b068898.txt">Table of n, a(n) for n = 0..1000</a>
%e 2415 is a member with 2+4 = 1+5
%t dsQ[n_]:=Module[{idn=IntegerDigits[n],len=IntegerLength[n]/2}, Total[Take[ idn,len]] ==Total[ Take[idn,-len]]]; Select[Flatten[ Table[Table[(n(n+1))/2,{n,Ceiling[(Sqrt[8 10^i+1]-1)/2],Floor[ (Sqrt[8 10^(i+1)+1]-1)/2]}],{i,1,5,2}]],dsQ] (* _Harvey P. Dale_, Sep 29 2011 *)
%Y Cf. A068896, A068897.
%K easy,nonn,base
%O 0,1
%A _Amarnath Murthy_, Mar 21 2002
%E Corrected and extended by Harvey P. Dale, Sep 29 2011
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