Triangular Number Pairs with Triangular Sum and Difference/Examples/T1869, T2090/Mistake

Source Work

 * The Dictionary
 * $1,747,515$
 * $1,747,515$

Mistake

 * Together with $2,185,095$ the $3$rd pair of triangular numbers whose sum and difference are also triangular.

This pair is very far from being the $3$rd such pair. In fact, ordered by the larger of the two elements, this is in fact the $26$th such pair.

Also see

 * Triangular Number Pairs with Triangular Sum and Difference/Mistake, where the source of the error is explained.