OFFSET
1,1
COMMENTS
The sequence is unbounded, as the (10^k + 9)-th triangular number for k>1 is a term.
The sum of the digits of triangular numbers in most cases is a triangular number.
Conjecture: For every triangular number T there exist infinitely many triangular numbers with sum of digits = T.
MATHEMATICA
Select[Accumulate[Range[500]], Total[IntegerDigits[#]]==28&] (* Harvey P. Dale, Aug 30 2015 *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Feb 21 2002
EXTENSIONS
More terms from Sascha Kurz, Mar 06 2002
Offset changed by Andrew Howroyd, Sep 19 2024
STATUS
approved