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%I #8 Dec 05 2013 19:55:10
%S 78,276,465,528,780,861,1176,1275,1653,1770,2346,2850,3570,3741,4371,
%T 4560,5253,5460,6216,6441,7260,7503,11175,12246,12561,14028,15225,
%U 17205,20706,22155,24090,24531,26106,28203,30381,32640,33153,35511
%N Triangular numbers with sum of digits = 15.
%C 1. The sequence is unbounded, as the (2*10^k +3)-th triangular number is a term. 2. The sum of the digits of triangular numbers in most cases is a triangular number. 3. Conjecture: For every triangular number T there exist infinitely many triangular numbers with sum of digits = T.
%t Select[Accumulate[Range[300]],Total[IntegerDigits[#]]==15&] (* _Harvey P. Dale_, Oct 09 2012 *)
%Y Cf. A068127, A068128, A068129.
%K base,easy,nonn
%O 1,1
%A _Amarnath Murthy_, Feb 21 2002
%E More terms from _Sascha Kurz_, Mar 06 2002
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