

A068128


Triangular numbers with sum of digits = 6.


6



6, 15, 105, 231, 2211, 3003, 20301, 112101, 2003001, 122000010, 200030001, 20000300001, 2000003000001, 200000030000001, 20000000300000001, 2000000003000000001, 200000000030000000001, 20000000000300000000001, 2000000000003000000000001
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OFFSET

0,1


COMMENTS

1. The sequence is unbounded, as the (2*10^k +1)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.


LINKS



MATHEMATICA

Select[Accumulate[Range[20000002]], Total[IntegerDigits[#]]==6&] (* Harvey P. Dale, Jun 05 2012 *)


CROSSREFS



KEYWORD

base,easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



